Gorilla: The best game from Microsoft
If you never played it, you can find all you need online. Go for example here and download the file qbasic.zip. You have to uncompress it, call a command line and execute the following inside the directory where you've put the files:
If you did it right, you'll see an introduction and be asked for the name of the players.
If you want to have some fun specifying the gravitational acceleration, you can choose one value from the following table or enter a negative one:
Now you are ready, just enter the angle and the speed.
If it is getting boring, try to hit the sun and see what happens.
or check out the fan-games Jorillas and Gorilla 2: The Return.