Great game in a classic genre. Audio and music well made. Sound and music in this game, is half the experience.
At times it was hard to see what possible to pick up, and what is enemy shots. Perhaps the hard to see difference in all the clutter it's part of the game?
The lag people are talking about seems to be related to the mouse routine itself. With the keyboard, the lag didn't exist at all. With the mouse, the lag only happened while moving the mouse. (Mouse movements causes the CPU to hit 100% load) I'd guess the mouse update routine is a bit too fast.