Geothermal

The lighting is really flat, I'd recommend changing it to something like KorhalPlatformEx2
Zergs cant effectively 3 evo walloff at the natural, and it looks like this grate should block pathing. If this were true and moved back a bit, you could have a 3 evo walloff. https://i.imgur.com/6EYpyRy.png
There is a major problem with any four player map, and that certain spawn positions will favor specific races in a given matchup. In your map, imagine a Zerg player spawning TL, and a Terran player spawning TR. The Terran has a must easier time harassing the Zerg, because the Zerg will expand away from their opponent, making it hard for them to defend their bases effectively, with less effort from the Terran. On the other hand, if it was Zerg BR and Terran TR, this is a bit more defensible, but still unfavorable (Zergs generally dont like taking triangular bases due to stuff like warp prism harass.) This is effectively the reason 4 player maps are avoided, so this map might be best saved for a future time.
I'm not a fan of the debris tower positioning, I think it could be used instead to provide cover for the horizontal fourth bases, since they're so forward. Perhaps something closer to this: https://i.imgur.com/q7VCUwM.jpg
The triangular base is also incredibly open with that lava rock path (which is a bit hard to see, due to its busy texturing). This might be fine for Horizontal engagements, but I worry about its utility in cross spawns.