> Pay attention to light. If you're in darkness, nobody can see you (unless an enemy gets suspicious and uses his laser scanner thing)

> Holding the right mouse button lets you pan the camera around, allowing you not only to look ahead to plan your attack but also to use ranged attacks on enemies rather far away.

> You can send elevators to a stop without being in them by standing in front of it, scrolling to the next stop and clicking on that stop.

> Your sword will kill any enemies it contacts on its return journey.

> If your turn ends and you are in mid-jump near an enemy you can attack that enemy, ending the jump prematurely.

> Turn-based combat only starts when an enemy spots you. You can take a lot of enemies out before then (even loudly) if you're quick enough.

> And finally, possibly the most useful trick, is to use pause a lot in real-time mode. Holding space and releasing it for a split-second will really allow you to sow lots and lots of havoc among enemies before the fight begins in earnest.

Hope this helps you. Have fun!