This is a redstone version of Lights Out , a 90s handheld electronic game. You have a 5 by 5 grid of lights, which turn on and off when you press their buttons, but each time you press a button, neighboring lights invert their state. It's a challenging puzzle to solve, either turning all lights off, or all lights on. Sometimes it feels a bit 1 step forward 2 steps back.EDIT: Updated 9/12/2020I decided to update this, since I've had an improved version for a while now, and I recently got back into MC.The new version is 4x4x7 blocks per segment. No pistons, and the circuit runs as fast as I could get it. Uses 2 hoppers pointing at each other, with 1 item in one of them, for the memory unit. This is about as compact as I think is possible, but feel free to improve it if you can. ;)BTW, Some of this info below is outdated now.Note: After pressing a pressure pad, wait till it pops back up before pressing another one. The circuit is as fast as I can make it, but if you run/walk across the buttons before the signal reaches neighboring circuits, it will mess up the way the game works, and neighboring nodes may not turn on or off properly. It shouldn't break anything, but it might mess up solution patterns if you were trying to play seriously.Also just FYI, I think you could switch the pressure pads with buttons, and it should still work the same, now that buttons can be placed on any surface.Outdated stuff:I've included the schematic files for both the full 5x5 game, complete with reset switch wired up, and an individual segment of the circuit; A 4x10x4 light segment that functions on its own and is horizontally stackable, so you can customize easier.With the individual segment I included, you can make different sizes of the game, a 3x3 light grid, which is more like the old 70s game "Merlin - Magic Square", or even a 7x7 or 9x9 (I think odd numbers are important). The different sizes alter the challenge of the game.Just don't forget to wire up the green reset lines, or you wont have that function. That same green line could also be used to send an 'all on' pulse, after resetting, if you make it, to set the game up for the next person. I've left it more manual for now, but might add that later. Update: I added an xtra schematic file with this feature!Anyway, I hope you enjoy this, download and play with it! Feel free to alter it, or improve it, just give me credit and let me know. ;)