KBreakout is a game provided by the KDE Games suite.
I love playing it and after going about 15 levels into it, I got interested in a few mechanisms and decided to fool around with its code. Turns out, something sinister is hidden within it 😉
To enable the cheat mode in KBreakout, simply run it as the following (on *nix):
export KDE_DEBUG=1; kbreakout
Game should start as normal but now you can use L and S keys to add lives or shift levels incrementally. Use it wisely; I do so to explore levels (Turns out, hacking/adding levels is easy too!)