Thanks for the comments !
Yeah I got some feedback for friends asking why the keyboard does not work : it's a design choice (but maybe a bad one ahah), but I felt that the game would be way too easy with keyboard (even if I reduce the timer for the aliens).
As for the raybeam, it's just because there's so much that you can do in three hours ahah. Initially I had thought of pretty cool animations combat and stuff... but heh !