Here is the Alpha 4 version of my game. Really much more fluid. Thanks again for your feedbacks about the previous release.
The most important optimization concerns the lights... So... during optimizing my game by making different tests I discovered that if you spawn a light object, it can be spawned only one time so I don't have to make a script for spawn/unspawn/respawn for light... only a Near sensor and addObject actuator to spawn the lantern light near the player :-)
I mean, if you spawn the same light in another place, the previous instance is automaticly destroyed.
It works very well and the game is really much more fluid. The game will be Free so share if you like :-)