Support arrow keys in lumines

The current controls are wasd + space, which anecdotally seem non-intuitive to most people. It's non-trivial to support arrow keys using the current framework, though.

The issue concerns the lumines game's WASD and space controls; start by locating the game's input-handling entry point and checking how the current framework processes keyboard input. Determine whether arrow-key support is feasible within that framework, then verify that the arrow keys control the game without breaking the existing controls.

Written by the indexing model from the issue text.