Interesting start of a game.
A few thoughts:
The tutorial shouldn't be mandatory, nothing here is really new for an experienced gamer.
The timer should probably stop when you reach an exit portal. Watching it time out because the portal loads slowly is annoying.
On the level finish screen watching the seconds (and other score) tick by that you just played is annoying. Either speed them up drastically, or just show the total, no real reason to count them. Currently, it takes almost as long as the level itself.
This can be skipped, by hitting the button.
If you start commenting down here, the game becomes deselected and you can't move around anymore. Everything else seems to function, choosing talents and directional firing, but not movement. Only way I figured out to get back in is to load the web page.