Portal Forum

For some reason after playing fabulously for 18 extremely satisfying levels, Portal has decided that level 19 should be an unplayable wonderland of impenetrable blue fog. Bonus points for the fact that there are mysterious explosions in the distance and that walls render, if at all, as floating triangles.

I'm just confused about the fact that the first 18 levels are completely fine, yet the game essentially breaks after it finishes loading level 19. I've tried redownloading Portal in the hopes that maybe it was just corrupt, but no such luck.

It might be that level 19 uses a certain graphics function for the first time, and that graphics function is not compatible with the video hardware in your MacBook. You might try passing -dxlevel 80 as a launch option. Note that "-dxlevel" is a sticky option. If you remove the option, Portal should remember the setting. If you want to switch back, you will need to pass "-dxlevel 81" once.

You should also check the graphics settings in the game options. See if fiddling with any of those makes the level render properly.

Have you resolved this issue? I just finished the game on my MBP with XO Games 7 with it set to -dxlevel 80. The graphics weren't that great but it worked fine.