Yup, I have just finished implementing first iteration of mountains.
Took me a little longer than I expected but it required heavy rewrite of map engine and editor.
On the video below you can see some basic mountain mechanics:
1) You can only jump down
2) If you do something stupid near the edge, or someone hits you - you fall down
3) You can shoot down from the mountain while projectile being shoot from the ground are blocked
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