I know these are relatively simple questions, but results on these forums are relatively quick. Don't worry, people who give me good tips aren't going unnoticed.
How do I add fog in a map (I already have a fog tag ready)?
Blast doors and cryobay doors from A10 don't open, how do I fix them?

For the Fog question.

Create a plane in 3ds max that will cover just beyond the area you want fog in. You can elevate it however you like, but I'd keep it a few feet off the floor. It really depends on what kind of fog you are making.

Open up the Material Editor and create a new ID. Rename "Material #" to "+unused$".
"+unused" is reserved for special material, the "$" makes it a fog plane.

Turn the plane into an editable mesh and give it the same ID as your fog material.

Attach the plane to your reference frame and compile the map

I believe that's all there is too it. If you are making it fog for underwater, place the plane equal to your water's height. In the tag, check "is water" under "flags" at the very top.

If you are making fog for a deep pit, look to Assault on the Control Room for some good reference.
Edited by DarkHalcyon on Jan 3, 2012 at 09:00 PM

How to add fog in Sapien:
Open Mission and you should see at the bottom "Cluster Properties". Open that and you should see "Fog", but don't open that yet. Open "Palettes" and click on "Fog palette". Click on "New Instance" and then enter a name for that, and select your fog (example: levels\test\chillout\chillout).
Then go back to Fog in Cluster Properties, then select the fog that you named.

The doors you are using have to be .device_machine tags. Open them and scroll down to $$$ DEVICE $$$ and scroll down again, looking for "automatic activation radius". Set it to 2.2 or the distance you want. If you get that near to the door, it should open.

I added a fog tag to the palette, but the button to show the list of fog types in the "Fog" tab remains gray (I can't click on it and open the list), so I can't change it from "NONE."

Use Kornman's hacked version of Sapien.

Doors work now, they were flagged as platforms, not doors. Fog is still a no-go (screw fog, all it does is make things hard to see).
Edited by ReconNinja117 on Jan 7, 2012 at 07:28 PM