This is a RTS / Flight sim hybrid game I've been working on from 1999 until 2001. It's completely written from scratch in C, using some of the most hideous code you've ever seen. Development started using 3DFX Glide and I switched to OpenGL as soon as the first GeForce 256 card became available. You'll find screenshots spanning from the first 3DFX triangle down to the very latest OpenGL version.
Notably, this game had large terrain with LoD, a very detailed soundscape, dynamic weather and a day/night cycle. Multiplayer was started but is buggy. There's also an online masterserver and an auto-updater in there. I'm surprised this even works still. There's also a very simple AI that just attacks you.
Basic gameplay: You have to destroy the enemy command center, and defend yours. You can build generators, defenses and even an orbital strike uplink. Firing a targeting missile at an enemy building will start a countdown after which an orbital strike will hit.
Here's a selection of screenshots for your enjoyment:
