Landfall has a unique layout designed to alleviate the frustrations many players have with CTF in TF2. In my experience, CTF matches on official maps often turn into a drawn-out stalemate in the center of the map, with the flags far away inside of easily locked-down rooms. On top of that, teams often get split up while juggling offense and defense. The result is that teams don't naturally work together and make strong pushes through choke points, and the objectives (the flags) are not the center of players' attention. These are 2 problems that are not present in other gamemodes in TF2.
Landfall's layout avoids these pitfalls. First, I decided to place the spawn points behind each team's flag. Much like in 5CP maps, players can run straight out of spawn, and they will always be going the right direction no matter what's going on. To accommodate the spawn points, I made the distance between the two teams' flags shorter, and widened up the map. This shortens the run-times to fights, but keeps the map big enough to stay interesting.
I also decided to make the flags relatively easy to grab, but difficult to return to your base, so that they would play a larger role during a match. I made the areas around each flag spacious to make sure a team's flag couldn't be locked down by an engineer. To make the return-trip difficult, I made all routes pass through the arena in the center of the map. That way when a team's flag is taken, there will be people in mid ready to stop the courier.
It took a long time to play-test and revise the layout to make all these designs work. In the end, I'm very happy with how Landfall plays! It feels different from CTF maps that came before it, and my friends and I have had some great matches on it.