Water elements 
?
The GDC one skips to 1:18 if don't like watching the whole thing

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voraga is dead - the person who made it (can't remember who) broke it "irreparably"
as for the second video.... what the hell? what is that and if that's an early version of legions then how did it turn out so different and so much smaller, and with no water?
one small step sounds like it would be great fun, but i think it would need quite a bit of changing to stop it from being unbalanced (think of people getting from one base to the other in mere seconds)
lastly i love the suggested maps... just not the pictures.
moon - change in gravity would be silly.... but maybe inside a GIANT moon station... think project eden styled domes, with different compartments (maybe even different environments)
city - like, but just HAS to be a post apocalyptic city, maybe leading to to some lore for you lore-nerds
tropical islands - WANT, but how would water be handled? maybe just shallow water, and it must have some cool effect such as water flying up behind you like this -