Silicon Vampire Jun 11, 2016 @ 1:57pm. Portal runs on the HL2 engine but no, you can not run those files directly. #1. debtgrips Jun 11, 2016 @ 2:13pm. portal runs on the half life engine and borrows some textures frm half life and borrowed alot of models/textures in beta so mabye its a file that was left in by accident. or mabyeno it cant be. My Garry's Mod is also stuck on DirectX 8, and I don't know why! #4. Wiwi Jul 11, 2013 @ 9:20am. Go to your steam library, right click on hl2, click on "properties", go to the "general" tab and click on "set launch options". In the box that appears type -dxlevel 90. Click OK, and then start the game. Just remember to remove this from the launch .

half life 2 launch options