What am I doing posting an idea here when I already have two in the works and recently dropped one?
Well, fact of the matter is, I have 2 forums that I frequent right now, and 2 that I can remember that I used to but currently don't; For a grand total of 4 eligible forums. One of them is... less active than the other 3. But quite an active community nonetheless. I would have preferred 12 forums...
But I digress.
Cross-Forum Robot Deathmatch!
A large list of parts is created, from which forum members may build fighting robots; Each robot is roughly the size of a pop-can. As well, the robot's response to stimuli is created. Once the designs are finalized and submitted, 2 robots from each forum are taken and set against each other in a 8-way battle royal. Multiple matches can be done at once, if enough designs are submitted.
Players and forums cannot directly control their robots once in the arena. However, their robots gain their forums points based on their actions, which may be used to purchase boons, which arrive in a fashion similar to the silver parachutes from The Hunger Games.
Robots are powered by packs that are generally in their chests... assuming the design is humanoid. Most are. The packs have limited energy, but by taking the energy from another bot, they can recharge. Whether this is their opponents, or Simulated Wildlife, they can continue operation through defeating another robot. No energy can be gained from a robot that ran out of power completely, however. Robots also make their decisions through a computer module located elsewhere; generally a head-structure. Separating this from the robot will make consumption of their energy easier by keeping them from attacking your robot back.
Power is delivered from one module to another through connections; either mechanical, or electric. Electric connections are basically wires and don't actually allow a module to move, but by putting a motor in the module or using a motorized module, you can use electric power and convert it into mechanical power at the site. Mechanical connections are clusters of interlocking gears at the connection between modules, that allow the module to receive power directly from the previous or next; but the power cost increases for every module between it and the source of mechanical energy, whereas electrical connections do not increase the cost based on distance. A balance between electric and mechanical energy distribution is required. There is another kind of connection, but it does not power anything. It is a computer connection, allowing control over the modules. Electricity isn't just used to control motors, though. Also, mechanical connections are complex enough that control is implied through which gears are turned.
The connections are built into the modules; Connections also have sizes, and can only be connected to the same size connection; but for connections with multiple sizes, can connect as long as they overlap. Additionally, a module may have multiple locations for modules, and slots for motors or accessories as well.
Let's take an example. The "Torso A32" module has a size 2-3 mechanical/2-3 electric {C} connection for each shoulder, a size 3-4 mechanical/3-4 electric connection at the neck, and a size 7-9 mechanical/8 electric connection at the waist (As well as a battery slot and a motor slot). The "Ext-Spine Naga" module has a size 7 mechanical/7 electric connection on top, a size 6 mechanical/5 electric connection on the bottom, and two accessory slots.
Can you guess where the spine can connect to the torso? Yes, at the waist. However, attaching further modules below the spine and putting a motor there would be useless, as the electric connection does not match. However, mechanical modules would match up enough that it could move.
The player contribution:
Participation of forum members would be encouraged. Each forum member has a budget, and can only buy so many modules. Usually not enough for a whole robot. Each who joins allows the forum to build more expensive robots. Sponsors of the robot fighting rings would pay attention to robots built on lighter budgets, though, and players would earn more by submitting leaner robots. Sponsors are NPCs and possibly designers of the non-competitive robots roaming the arenas, or even of the arenas themselves. However, despite their interest in the rings, their real interest is that they own other companies, such as oil companies, soft drink companies, software firms, or manufacturers of robot modules. You attract their attention better by appealing to their interests. Build a robot out of just one manufacturer's parts? They might give you more cash. Paint it to match the soft-drink company's logo, or program it to recreate the logo? Yep, more money from them.
This means that the forums with higher player participation will be at an advantage, due to increased initial funds from more players. But that's part of the point; as well, price rises faster for modules than their effectiveness or usefulness. Also, I'm aware that some players may attend multiple forums, sometimes under multiple names. They should keep in mind they'll be competing against themselves, but I won't disallow them from contributing to multiple robots.
If it isn't obvious that this is a humane simulation of a certain series who's name I've already dropped, you can probably figure it out by now. Except that instead of a post-apocalyptic world with an evil government, it's a highly commercialized and industrialized world with a large number of hobbyists and enthusiasts. And instead of children fighting to the death for survival, it's robots fighting for endorsements.