I've fixed this up for 3D, and it looks great! You can get some really good toyification with the convergence cranked up, turns out tower defence games are really well suited to 3D! Big thanks to bo3b and DarkStarSword, who deserve most of the credit for helping me work it all out.
Updated 10/7/15, working again now.
Download the fix: DefenseGrid2.rar
- Halos for water, fire, some lighting effects
- Minor lighting problem in Mission 19
- Extract rar to the game directory (\Steam\steamapps\common\DefenseGrid2)
- Hold Z during the introductory level flythroughs for a more comfortable convergence
- Run the game
If you need to raise/lower the convergence while holding Z, look for the following section in d3dx.ini:
Key = z
convergence = 15
separation = 100
type = hold
You can modify this to change the key, or adjust the convergence