One can get infinite skill points just by reading
repeatedly notes of that scientist at first level (escaping from science lab). Notes are inside file cabinet
in some dark room with glass walls (3rd floor).

A similar bug is in the tower level where you can do the banzai jump. Everytime you do the jump you get 1500 points.

yeah, if you manage to avoid dying...

that's easy. when you go up the stairs, DON'T turn left onto the plank. that thing is a death trap. instead, jump straight ahead over the fence, then go around the corner and stand UNDER the plank before jumping down. after a couple of seconds, you should find yourself in the lobby, facing the receptionist with 1500 more skill points to work with.