I still managed to find a spot somewhere at the rim of the map where I could fall off into the void (and I guess there would be more to find...)

Maybe if you added a safety-net plane under the level that would respawn the player (or at least detect the death condition and trigger a game-over) when collided with would be a simple solution to at least prevent the game from breaking...

And maybe change the game's page so you don't have a screen-width of place-holder for the game to start in when eventually the player would probably go to full-screen to play anyway...

Moving and jumping worked fine with a PS3 controller, but there was no way to turn around. Please consider adding input processing for a secondary thumb-stick for it.