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ok to draw a square on the screen, us can use the box command, and, if you want it to be a hollow box, draw a second box slightly smaller
ex.
box 0,0,640,480
box 1,1,639,479
for your second question. Yes it is possible, except for the last part about a
simple programming language. While it can be done, it would probably be anything BUT simple.
As for the grim reaper, check turbosquid.com and (when they have finished updating their site)www.polycount.com. They have a lot of game character models for various games (jk2, ut2k, ect). All you have to do is get the model out of it and convert it to a useable format (easier than it sounds, for conversion, use quick3d)