In an FAQ, Valve said is wants to have the TF2 community involved early in the development process, so it can gather feedback while it tries "variations in the map layout and game play mechanics".

Valve has big plans for Team Fortress 2's next update, starting with a couple of new maps and fixes to some of the more easily-exploited existing layouts. Two new community-created maps by Ian ...

It featured some memorable map layouts, such as the now-iconic 2Fort, and some novel new features, like the Nemesis system. But Team Fortress 2 rapidly became known for its Source-based animation ...

the patch notes for this update list a few small edits to certain map layouts, as well as a positively massive amount of bug fixes. The summer update arrives after a tumultuous time for TF2 ...

Why have there been so few Team Fortress 2 maps released by Valve ... an individual too advanced for your average, straightforward layout. With five capture points spread out in a D-pad formation ...

The second official Capture the Intelligence map for the PC version of Team Fortress 2 may arrive as soon as ... the reworking sports the same basic layout but removes the Control Points of ...

Just like last year's TF2 summer update, this one is chock full o' stuff made not by Valve, but by the community: 10 new community maps (Embargo, Odyssey, Megaton, Cachoeira, Overgrown ...