Just tried it with my smaller wacom and a quick hack (using absolute mouse position) and for me it's harder too play with it than with a normal mouse, exspecially to hook and shoot (:
(also exhausting^^)You can still set the pen to mouse mode in your settings, but well I dont think it's worth 'abusing' a wacom tablet for playing
It's not cheap and the surface will have much scratches and you will probably have to buy a new pen after a while. A normaler mouse is cheaper and more effective imho
I'm using their cheapest model, Bamboo Pen, and it seems durable so far. Maybe the scratches thing is a problem with some other model, havn't noticed anything like that yet.
Mouse mode would kinda defeat the purpose I think, since it would ruin one of the main advantages a pen has over a mouse. Namely never running out of space to move physically in.
You say it was a quick hack? That's hope inspiring
. Perhaps I could actually do it then. I havn't really contributed to any open source project yet though, so I don't really know how it works.

It's not cheap and the surface will have much scratches and you will probably have to buy a new pen after a while. A normaler mouse is cheaper and more effective imho