Basically, my Pockets map is going to have a hidden time limit, at which the end of the limit, the exit portal is disabled and then it'll fade to black w/text telling you why you've failed and then loadsaved.
Initially I was just gonna have it fade to black w/text and be done. But then I realized that one could be heading towards the portal and walk into it even as the screen is fading to black. So I would like to be able to disable the portal. I figure I can use env_render to make the sprite and beams invisible but I'm not sure what I can do about the actual trigger_changelevel brush.