Here is the full list of all 13 Swelter achievements.
Complete the bonus part.
Rob the Combine armory.
Tea.
Get killed by a train run at the very beginning.
Freedom is life not according to someone else's rules. Bet on independence.
It is easy to break one straw, but it is more difficult to break a bunch. Bet on unity.
Show your superiority in the air.
Find the AK left many years ago.
The attacking helicopter looks best on the ground. Bring it down.
Open all caches marked with a radio beacon.
He will not tell wisdom, but he will help find wisdom. Find a yurt with a vortigaunt.
Eliminate the missile turret.
Survive a failed train disembarkation.