How to Win at Kbounce

How to beat KDE's game Kbounce. With a little practice, you can rack up amazing scores, and a new technique makes it fairly simple to beat earlier world records. The higher the round, the easier it actually becomes. One name for this technique is the Roach Motel - the balls check in, and, with encouragement, keep checking in until they stay.


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    Make sure that Kbounce is installed on your computer. It's a standard game for KDE, which is a popular window manager for *nix systems (more information and installation files are available at ).
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    Play a few rounds, getting acquainted with the controls and how it works. The usual beginner strategy is to draw lines bisecting the playing field, eventually enclosing each ball in a space small enough so that 75% of the field is blocked off, completing the round. This is fine for new players, but once you've mastered this, it's time to change strategy and start building toward higher levels and more serious scores.
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    This article will be using the lower left corner as a start point in describing techniques, though the strategies will work at any corner, and possibly even vertically (though horizontal traps are much easier and more useful).
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    Place the cursor, with horizontal lines selected, on the fourth row up from the bottom, at least 8 columns away from the left edge. Start a line when neither ball can intersect your left-side line before it's completed, trying to catch a ball with the head on the right, making a longer line and conserving a life. This will give you a line part of the way across the field, with three spaces between it and the bottom of the field. Switch to drawing vertical lines, and when a ball bounces into that corridor, draw a vertical line behind it in the 4th column from the end of the corridor, trapping the ball into a 3x3 square. You should have enough space in the corridor to trap the second ball in an adjacent space, closing off the entire rest of the board. To save time, draw a vertical line above the end of the corridor when it's safe to do so, closing off the space above and reducing the area the balls can be in. The field should look this.
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    For level 2, with 3 balls, start the corridor 4 additional spaces to the right, making room for the third ball to be trapped in the corridor. It's fairly easy to leave a perfectly square space outside of the corridor, in which case, the balls will bounce off of the same parts of the walls, never entering the corridor. To correct this, draw a vertical line adjacent to the right-hand wall, narrowing the space by one, giving the balls a new trajectory so that they precess around the edges. This is also how to correct the situation of the balls regularly bouncing near, but not into, the corridor.
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    For round 3, with 4 balls, a single corridor is possible, but tricky - so make two corridors, stacked, as shown here. Continue in this vein, adding corridors until you have enough space to trap all balls, for a few more rounds. You'll find that you can have 4 corridors 3 spaces wide, with one 2-wide corridor. In the two-wide corridor, continue to leave the balls spaces 3 wide to be in - a 2x2 space is possible, and results in a higher score, but is tricky, and not really essential. Your goal isn't to have a great score at level 16, it's to survive until about level 20, at which point you'll change to a new technique where score is maximized. It's pointless to risk losing the game for a higher score at round 12 when your per-round score later will easily go over 7,000 points. As your confidence grows, you can start using 2-wide corridors more extensively, though you probably won't have enough time to do so before round 6 - balls are less likely to enter a 2-wide corridor. Practice terminating lines by hitting balls rather than the lines being intersected - this skill will become very useful, then essential, later in the game.
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    With the box-trapping technique, it's possible to get up to rounds into the mid-30s, though it becomes essential to trap balls in 2x2 areas and trap multiple balls in these areas to continue to clear 75% of the field. In earlier versions of Kbounce, in which 1-wide corridors were useful, that's how the previous world record was set, with a double-ball per square technique. That's not necessary, though - the new technique will trap an unlimited number of balls into a 14-space area, letting you clear 97% of the field. You'll have the lives and time to start using it by the time you're at round 20, though time constraints make it iffy before round 15.
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    By now, there are enough balls to make it almost impossible to draw a line all the way across the field with one try, but there are enough balls to draw a partial line that does not reach any wall, and this is what you're going to do. Use your skills at ending lines by hitting balls to draw a line in the third row up from the bottom, ending it 2 spaces from the left wall. Ending it a bit further away isn't a serious problem, as long as you've got the line started. Growing the line a few spaces isn't tough, and you've got enough lives to spend doing it. Be careful to not reach the wall - at least 2 spaces between the wall and the line are necessary. If needful, just draw the rightward-headed line when you know the left-headed line will be killed before it reaches the wall - you've got several lives to play with, a few lost making this first line won't hurt.
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    Now draw a line that does end at the wall, on the 6th row from the bottom. This line doesn't need to be very long - 4 spaces long is ideal, 3 long will work, and longer than 4 will work as well, though the closer to 4, the better. You just need to overlap the first line by 1, so you can close off the pattern to end the round. If your first line doesn't end exactly 2 from the wall, now is the time to draw vertical lines adjacent to the left wall below your second line until you've moved that section of wall to leave 2 spaces between the wall and your first line. Your field should now look something like the picture. Once you've got this done, complete your first line all the way to the right wall. Be careful of balls bouncing along the corridor you've formed, and expect to spend a few lives doing this. Balls will have begun to accumulate in the left end of your "Roach Motel" trap. Some will stay immediately, and some will bounce through the trap, down the bottom corridor, and then back to the trap. Some of these will be caught, some will bounce right back out. If more bounce back out than not, adjust the length of the bottom corridor by one. Try to start with an odd number for the length of this, as it seems to work best. See the tips sections for reasons that balls behave differently in the trap. If you got a perfect start, closing off the last two spaces of your bottom corridor will cause all balls entering the trap to remain there, and your screen will now look like the next picture.
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    If you make a mistake, it's not a crisis - just build the trap in another corner, and build vertically to block off your first attempt. If all 4 corners get messed up, close off the top or bottom to make 2 new corners to try in. Slow and steady does it - overconfidence has given me plenty of practice in correcting for errors. Once you've got the trap built, the level is pretty much won. At the very worst, you should be able to close off enough to make 75% and get a fresh round and fresh start, even if you make minimal score on any particular round.
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    As rounds progress, it gets pretty crowded in there. Slow but steady is the key. At this level, the worst mistake to make (and easiest, after having your line totally killed) is to add onto a line so that your join square is killed, but you make other progress in building the line, leaving a 1-square gap, like this:
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    That one square cannot be filled in a useful fashion, and the resulting corners disrupt the flow of the balls. Sometimes you can abandon that trap and build another, other times you'll need to construct workarounds to trap all of the balls. Inconvenient, but not fatal - even with several bad traps, you can finish the round and start again with a fresh slate. If you stay calm, you can, at the very least, survive any round, no matter how badly the play has gone. (Note: In later versions of Kbounce, by ver 0.11, filling that single square is possible, so this problem becomes a non-issue.)
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    After the trap has been completed, you can relax - most, if not all, of the balls will fall into it without further intervention on your part. If the last few balls keep bouncing back out, change the length of the trap's tail until they behave. If they simply won't enter the trap, adjust the field until they do. Start adjusting the field by filling the space above the short wall of the trap vertically, as soon as traffic is light enough to make it easy and safe. Once that is filled, after you're sure the remaining balls won't enter the trap, adjust the wall furthest from the trap entrance one column at a time.
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    If you get a perfect start, and the short wall is exactly 4 blocks long, the balls will eventually orient themselves into a pattern like this. If the left end of the long wall of the trap ends 2 spaces away from the outside wall, filling 2 spaces at the end of the trap will retain all balls that run the corridor. As you can see, most balls (the major line) are bouncing from the top outside corner of the short wall to the inside corner on the lower right, while the rest (the minor line) are bouncing from the bottom outside corner of the short wall, through a loop bracketing the inside corner at the lower right, to the inside corner at the top of the short wall, where it returns. Given enough time, all balls that don't enter the trap will align themselves in these lines. Once that's done, it's fairly easy to get them all into the trap pretty quickly.
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    Wait for the longest space between balls in the minor line (the one that bounces off of the bottom corner of the short wall) and fill the first two columns to the right of the left wall (pretty easy with almost all of the balls busy elsewhere).
    • If the first balls bouncing out of the previous pattern will return before all of that line has bounced out of the pattern, draw a partial line above the track, filling only the leftmost four columns, and letting one of the balls still in the minor track kill your line, so it looks like the "Part-way through..." screencap.
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    Once all of the minor line has bounced onto the new track, finish filling that column (you have to wait for a gap in the major stream, and start very close to the end of the short line).
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    The major stream will start progressing around the field, along the same track that the minor line took. After about 4 circuits that track lands directly in the mouth of the trap. Some of the major line will hit the corner and bounce back out - generally less than half, though it really doesn't matter. Those remaining few will take about 9 circuits of the space, then enter the trap.
    • Even if your beginning isn't perfect, as long as you have a functioning trap, you're going to win the round. You've got plenty of time, and plenty of lives, so relax, but do keep an eye on those seconds - when you're down to 300 seconds, it's time to start getting serious about finishing the round.
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    To finish the round, once all of the balls are stable in the trap, close off the tail, then the main body. (Closing off the main body ends the round, and you want that tail closed first for maximum score.) That'll look like the screenshot 'All balls in the trap' just before you close.
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    Draw vertical lines just outside of the space taken by the balls to close off the other areas. This will leave you with a roughly B-shaped area of 14 squares. This will result in closing 97% of the area, for the practical maximum of bonus points for the level.
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    Be warned: this does become something of a long march. The current game of the original author, as for this writing, has been in play for 5 days now (not steady play, but fairly frequent), and each level now starts with over an hour of time to complete it. In passing the half-million score mark, the author squeaked in with barely 26 minutes to spare, and only 109 lives left - so you can see why the challenge is pretty much over. As this technique keeps you busy for a few minutes in the beginning of a round to set up the trap, then another few minutes of cleanup after the trap is mostly filled, there's a lot of time in the middle doing nothing but waiting for the trap to fill. Higher scores than mine will be made by people with more endurance than. Previous formulas to estimate the top possible score are irrelevant to this technique, because you can theoretically have an infinite number of balls in the 14-square trap. The top score will be reached when the software can no longer handle the numbers, or the CPU can no longer calculate trajectory and bounce for so many balls, and slows to uselessness. (In the example described here, the computer slowed considerably at the beginning of a round well before hitting round 100, though the seconds counter remains accurate. As balls stack in the trap, speed resumes.)


  • When filling space vertically, you can save time and lives by building one-wide corridors. Balls won't bounce into them, and they fill once the vertical line is completed. If you're adjusting the width of the field to change the trajectory of balls to bounce them into the trap, it's probably best to ignore this tip and only change the space by one at a time, but if you're filling space to block off a spoiled trap, this will work well for you.
  • If, after most of the balls are in the trap and the space above the short wall is filled, one clump simply refuses to go in, a quicker finish can be had. When that clump strikes the top left corner exactly, enters the trap, or bounces off of the corner of the trap , create a wall on the right to leave a field 22 squares wide and 15 tall outside of the trap. This will give you a 3-rail shot between the top left corner and the trap, with the corner changing the trajectory between entering the trap and bouncing off of the corner. Changing the length of the trap tail, one column at a time, will eventually cause the balls to stay in the trap.
  • There are two types of ball - think of them as clockwise and counter-clockwise. They behave differently when bouncing off of outside corners, and it's possible that these types are relevant to balls staying in the trap. Someone with better understanding of this issue (and what, if anything, will toggle the state of the ball) is welcome to add an explanation of that here.
  • At about round 100, it becomes easier to start the trap by building the short wall on the 6th row up first, and then building the left end of the long wall.

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Categories: Arcade Games | PC Action