The main challenge after that is the collision code and creating good cow graphics (possibly rotating them mid flight ).
Excuse me for being abit chicken, but I'll think I'll go for something either completely round or square (rock or brick).. If I decide to do something advanced like cows (hum, I get a Monty Python-flashback here somewhere) I'll let you know AliCow :twisted:

And Gravity should be possible to handle yes, thanks for the info.. I haven't started worrying about collision code yet :roll: