Hello, I am a game developer working on a science fiction video game. The game is intended to be vaguely scientifically plausible and I'd love some advice from someone with a greater knowledge of physics than me! In the game, you have a futuristic device that creates cubes of "energy". You can stand on these energy cubes, they simulate gravity, they can hit other real objects and move them, and can land on surfaces like the ground and such. They move with the Earth's rotation. However - they don't exactly behave like a cube made of matter. They don't have a center of gravity (if you had one stacked on top of another such that the center of the upper one had nothing underneath it, it would not rotate and fall down). They don't get damaged or corroded or anything. I also imagine them being "heavy". You could not pick it up, but perhaps it would move with sufficient force (say, a forklift or something) ... and of course you can see them. So there are photons all up in there too. Like a "force field" I suppose! If you wanted to give a semi-plausible explanation for this, what would you say? Are there any theoretical particles that have properties like this? Thanks for any help.