Some shareware/freeware pointers.

  • Warcraft II - The latest Internet shareware version (v1.20elc) while it has multiplayer support, it only has one map that supports up to two players. I think limiting the max players to 2 player might be needed.

  • Starcraft Shareware - There exists a mod called the "Ultimate Patch" which allows some form of custom content into the game. It usually takes the place of the .chk files for both "Loomings" precursor campaign and the only multiplayer map. "Byways"

The patch also allows users to play as the Zerg to a somewhat varying degree. (Only the Protoss are completely absent from the shareware)

See this reddit post for more.

  • Tyrian 2000/One Must Fall 2097 - Nowadays these two games are considered freeware, so it should be safe to have them downloadable on NukemNet. Download for OMF2097

  • Z.A.R. - Initially the gameDefs states that the demo lacked multiplayer. However I should clarify that there are multiple demo releases speeded over on the internet. Some of them date far back to 1997 found through coverdisks. The earlier ones lacked multiplayer support. But there is a demo version that dates to April 1998 that has multiplayer support. zardemo.zip

I should also point out that Z.A.R. has a Windows build that can be worth tackling. In the same link above (zar_3dfx) has binaries for the demo version. It supports Software (DirectDraw I assume), Direct3D and OpenGL.