Good to see you thinking about meka maps!
Maps don't have have to be larger, but they usually are outdoors. Not many rooms fit 20+m high robots, a very large warehous/factory, caves maybe, perhaps a huge alien spaceship.
The same things that make a good MP map for a mek game are the same as for any fps. At the SF wiki there is a page on mek maps http://sourceforge.net/p/mekarcade/wiki/MekMaps/
Many of issues are the same. How do I draw the oppenents together? How do I design it so it doesn't becoming to snipey? How do I give all the classes/weapons a role on this map? There are a few specific difference, as a rule in a meka game you don't have weapon pickups, but you have health and armor salvage or weapon upgrades.
The biggest change and the hardest to get your head around is scale
. In a mek game you are a big stompy robot, bit like the guy in the Godzilla suit who mashes Tokyo. I have been trying to finish off the MekArcade vehicle set over a couple of days, one of the reasons I have been trying to get them finished is they come on a map and they are mostly scaled for RE, but in one area they are scaled for a meka game. It's a good illustration of the difference.
In the images below the same player model is used, with the models scaled for a human scale FPS and then for a Meka game.
While on the subject of maps, I think we will start a MekArcade Map Concept topic (it would be best in a MekArcade subforum of RE. Hint, hint.) where people can post map concepts. They can be maps they have already made, modded or something new.
If you do something new I don't want you spending too much time on the fiddly bits, leave them, for the moment to Slartibartfast. The reason is because we will probably be using tesseract for lighting and at this stage I am in the dark about how much, if at all, maps with old lighting system will work.
There are a few concepts for maps that I would like you to start thinking about.
1. Believable Alien environments - I put this first because very few games implement alien worlds that are much different to earth, often they have trivial changes like purple sky and blue leaves. Nearly all use earth derived texture/models/forms. It would be fun to build a convincing, truly alien world. Meka are space rated and can operate in the cold vacuum of space and other hostle environments so just about anywhere is OK. If someone did come up with a fantastic concept map for an alien environment that needed some matching models or a skyboxes etc, we would be happy to have a go at it.
2. Earth like Environment Templates - a series of templates of common earth like planetery environments. Deserts, artic, fertile valley, alpine, beaches, swamps, savannah etc. A little sample terrain, the correct textures, approriate models and lighting. Again, if someone comes up with a killer looking map that needed some artwork to take it further, we could provide that. In the long term I want to develop templates with some sample map geometry, matching models and any scripted bits.
3. Beautiful maps. Beauty is it's own justification. Painting is dead, digital arts rule and there is no better tool than the cube2 engine. Some of you may be a digital Degas, a Pablo Picasso of the pixel. Make some art for us!