How about a game where you run around clubbing baby seals all the while being chased by greenpeace....
-> Start off simple, create a matrix, create some objects (cubes, spheres, whatever) learn to move them around the matrix, learn object collision, etc...
3-d is not that hard to start, but definitely learn the basics like movement, camera control, collision (a bit tougher to perfect), object interaction, etc...
sync on : sync rate 0
make matrix 1,1000,1000,50,50
make object cube 1,.05
position object 1,500,0,500
s#=.1
a#=.1
dist#=2 : ` distance camera behind player
height#=2: ` height above player
smooth=10 : ` smoothing value
do
if upkey() then move object 1,s#
if downkey() then move object 1,-s#
if leftkey() then yrotate object 1,wrapvalue(object angle y(1)-a#)
if rightkey() then yrotate object 1,wrapvalue(object angle y(1)+a#)
set camera to follow object position x(1),object position y(1),object position z(1),object angle y(1),dist#,height#,smooth,0
sync
loop
use arrow keys to move around....