So you just made a map. Your making a gametype for it too. You put the gametype so there is four rounds for... Wait what? I can't choose a different amount of time than what Bungie preset? Well actually, you can. Go to your map. Instead of slayer, make this game varient KOTH. Make the hill as big as your map, missing no boundries. So, basically it should cover your WHOLE map. Go to your gametype settings, on KOTH, and choose how many points to win. Remember 1 point = 1 second. So, if you choose 100 points, you game will last 1 minute and 40 seconds. Then, you start up the game as KOTH. This will be like slayer, because you'll always be in the hill. In theory, the person who kills the less will stay in the hill longer, because he won't have to respawn. If your dead, you can't obviously gain points. So, the team, or person with the most kills, will win. There is a flaw though. Someone could hide, and never die. So make no hiding spots. Problem solved. He will have to kill to stay alive. THIS IS NOT THE SAME AS putting a hill down and making walls around it to make a perfect cage.
I'm a bit confused. You need to explain this better, and give an introduction to what this gametype is supposed to accomplish. You wrote this in way that doesn't seem very logical, which doesn't help me to understand what you're talking about. I guess you're saying something about making a time limit in a Slayer game using KOTH. Huh?
Im pretty sure this was explained in a Forging 101 earlier. I'll edit if i find it. be back in a min. EDIT: Yep, found it, written up by TrueDarkFusion.
Darn. I thought I thought of this. EDIT-No, that's map size. NOT what I am talking about. I will re-write it, for people who can't comprehand as much.