I was trying to make a CTF game where both teams must race to the centre then grab the flag and bring it back to there base. So I forged the map, it looked nice, and looked like it would play good. But when I went to set up the game type I found there was no CTF type that would fit my intentions. So I improvised, I made it neutral assault and switched the bomb plant points for each team so you brought the bomb back and planted the bomb on your own base. it looked wrong but it played right. So what am I getting at? If you get stuck making a game type for your map remember to experiment with the capture/spawn/plant points. Or design a map around your own neverbeendone game type. Hope this helps.
Or you could've made it CTF but Instead of the flags spawning at your base, the enemies and your flag is in the middle so You can grab the enimies flag and bring it back to your base. That kind of makes a neutral Flag game.
You could've just done Neutral Flag and put the flag capture points in the opposite team's base. It's pretty simple.
Try this: Use your neutral bomb gametype and when you get back to your base with the bomb, make a teleporter that leads to a spot in the enemies base where the bomb will go off. I've made a map like this before, this is what I did.
But Its not the same While you are stealing their flag they can steal your flag. In my game I wanted all the focus to be on the single flag/bomb carrier, without having a couple of enemies carry a flag back through an empty map