I programmed this Chip-8 emulator in 2008 to learn more about emulation and the design of virtual machines.
The original Chip-8 keyboard is only a 4x4 button grid. Key bindings are written on the screen (sorry for the small text). You will probably need to play around a bit find out which keys you need to use in the various games.
(The default game Brix uses Q and E to move left and right).