Well, I've got some time to kill so I've downloaded your map and I'm going to point some things about it.
- Way too open. As already said by damfro here, this one is really gigantic. ActionCube maps are supposed to be set in realistic settings, mostly indoors or urban type of areas, not supposed to be so big and spacefull. And also, if you intend to do a map this big at least tweak the fog so you can see something.
- Irrealistic brush build. Your walls, stairs and rooms are really dull, also gigantic, some stairs I spent like a minute climbing up. The long, long, really long corridors are a pain in the ass, in deathmatch this kind of corridors is a mustn't. Another thing I must point is that all the walls are straight, gigantic and they lack detail. It's like one gigantic cube.
- Texture misplaces. Some of the textures you've applied are really out of place there, like a common error a lot of people tend to make. Bricks are not floor textures. When you choose a texture you have to really think about where you're applying it to, make it feel real and imagine it in real life, and then apply it.
- Map models, WTF. Okay this was really surprising. Mapmodels are meant to detail your map as long as they have a meaning for being there (And I tend to abuse map model usage). You have a whole temple thingy theme and you placed palettes and gas tanks around, they're all like WTF right there.
- Lightning. It's just meaningless. There are too bright lights around everywhere without meaning at all. You should put a texture that looks like a lamp, or a light source, and give meaning to those lights, and also make them darker.
Well, those are only some of your faults, I advice you to play through the original AC maps and learn from them, don't COPY them, but learn. From what I can tell you have worked in this one some time, It's not just a 3 minute map like others around here, but you have a lot to learn yet.
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The way of the R.T.F.M. (Read The Fucking Manual).