Giant Space Slug

Giant Space Slug is a Snake / Nibbles clone made in text-mode. Actually since this game was originally released in 1987 (this is v2.2 from 1990) this game predates Nibbles. The object is the same: Eat the things (here they are space ships) and avoid running into the walls or yourself. Each time you eat something, your tail grows longer. You're also timed here: If you take too long, you'll miss your chance and your target will move. That's pretty much all there is to it, although there are difficulty levels (harder = faster) so you can challenge yourself with that if you want.