Name says it all. I'm currently building a Sandbox varient designed to support a unique 'tower defense' gametype. Basically, it's on Sandbox open. The defending team spawns in the centre of the map, inside a tower that I'm trying to build as high as is practical. The tower is a veritable fortress, and gaining access won't be easy. A ring of chain-gun Warthogs, rendered immobile, provides effective close-range defense against air vehicles. At the very top of the tower is a Spartan Laser, accessible by teleporter. Only one laser will spawn at a time, and there is only enouch room for one person, who will block the teleporter so no one else can get up.

The attackers have to survive assault for long enough to get to the tower, and get inside the bottom area. From there, they plant a bomb next to a pipe. The pipe is filled with fusion coils, which will set off a chain reaction which heads to the top of the tower; countless fusion coils are hidden under the floor, making for a very satisfying fireworks display for the winner.

The defenders can't escape from the tower. Or, they shouldn't, because they cannot get back to their weapons, and so will be utterly destroyed by the attacking team.

The attackers spawn behind a barrier, and have access to a variety of weapons and vehicles. The vehicles they get will be:

2x Hornet (haven't decided yet whether to use normal or Transport)
2x Warthog, Gauss
2x Banshee
2x Mongoose

This large variety of vehicles lets the attackers choose whether to take the high or low road, so to speak. This is pretty much intended to be an arcade/practice gametype.

Heres an idea, do something similar to what you've outlined here. My only addition being make it LOTR(Lord of The Rings) Style. Essentially exactly the same thing except that instead of a tower make a wall with several different layers, Essentially its a Siege of Helms Deep if you know the story.

Yes, I was thinking of that, sort of thing, but I still want the tower to play a large part. I think this one is going to need a lot of playtesting.

well okay. Heres another idea. You want the tower to still play a part? So lets think about it. It's a fortress wall, fortress walls have towers on them too.

So here comes my idea, Still have your LOTR Basic design but modify the wall so that instead of having some plain wall it has two towers on it. Say your original tower was going to be 6 levels high. Make two smaller towers 3 levels high each.

Lets imagine tower (a). Okay in this tower you could have your anti-locomotion weapons. Laser, missile pod, stickies, trip mines, rockets etc.

Now lets think tower (b). In this tower you could have your anti-infantry weapons. Sniper, shotgun, AR, BR etc. In this tower you would also have some equipment that allows some base defense. This includes regens, power drains, bubble shields etc.

Now for the wall, This is where you unleash your inner forger. On the top level you can have things like brute shots for moving objects that are placed right on the edge, this would allow another degree of defense never seen before. Imagine it your casually sitting underneath the enemy trying to blow your way inside and next thing you know, your splattered by a falling box!

And of course there's your lower levels which would have as you've said your gun emplacements and so-forth. Also on the multilayered wall your have some basic equipment and weapons. Nothing to specialist though, things like smgs, BRs, spikers etc.

Now for the enemy base you'd have to have some degree of spawning protection to avoid being spawn sniped over and over. Now you could place man cannons placed in front of the wall. Now if your sticking with the LOTR theme id forge something to look like a catapult with the man-cannon to give it a siegey feel.

Now id also place some teleporters which would teleport you to some cover closer to the wall than your spawn point, but not too close otherwise there goes the challenge of the entire game. This would allow the attackers some small element of surprise as the defenders wont know where the attack will originate.

Now speaking about the game type. I would make it a 1 bomb variant. This would be because once you've blown their defenses to the sky you'd have to charge in there and plant the bomb(plants immediately, explodes immediately) therefore proving that you've "conquered" the enemies castle so to speak.

I hope all this makes sense, cause I'm playing halo at the same time whilst typing in between deaths and matches.

P.S This is all open to modification, if you feel one part is necessary whilst another just hinders it feel free to scrap it. Assuming you choose to proceed with my idea.

P.S.S Sorry bout the giant wall of freaking text.

problem: a single grenade could set off all those fusion coils, any explosive wepaon could.

Yes, Dthen, I'm trying to figure out a way to stop explosive weapons from setting off the fusion coils. I think that bomb explosions have a wider radius than a frag or rocket blast, so maybe that could solve this particular issue. And, Wagon, yeah, was thinking about having it so the attackers could throw Trip Mines out of man-cannons, or something. And, thinking of adding Thwomps, too.

Meaning, you have to walk through a passageway, and grab a custom powerup, which spawns a block, which then falls on you.