Duel

Duel is a two-player deathmatch game done in high-res text mode. One of its big features is a built-in editor which allows you to create your own levels. The game includes a wide variety of different objects that can be placed within the levels, and the color / character of each can be customized. However the game only includes one level set (ZONE.MAP) and I'm unaware of any other user-created maps available elsewhere. The editor is also not very intuitive to use (compared with something like ZZT for example. But if you have another person who's willing to play a 25+ year old textmode deathmatch game with you sharing the same keyboard, give it a shot!