I saw this awhile back and I've been meaning to make a critique of this, I let it simmer since it's a very original concept, and I see some things that look counterintuitive to me. I don't know if this is still useful to you, but here's my humble two cents.
The technique is great. I just love the way it jumps out and looks like a real object. The design is incredibly original, many people just go for a bigger gun or one loaded with electronic doodads and polymer construction for the futuristic look. You clearly went outside the box here, but put some thought into it and didn't go fantasy crazy.
At the same time, some things in this pistol are usually better suited for a rifle. The bullpup layout looks futuristic, it seems out of place in a pistol though since it's already a short arm and bullpup designs bring a host of problems for the only advantage of less size/more barrel length. I'm assuming maybe incorrectly that the whole slide reciprocates backwards, so if aiming it like a standard pistol it might hit you and fail to load the next round.
I can't quite imagine how the magazine change works out. The rounds just sticking out the back would get grimy or moist and foul the mechanism. There's no hammer (electric ignition?), and the layout seems like it'd give it an odd balance.
I think the magazine is the only piece that's really out of place to me. When you think about a pistol you need to consider firing positions and the way it'll be held. Torvenius has some really cool ideas, but the vast majority of his weapons would be unwieldy to use in a real world setting. The 45 degree angle handle looks really cool and futuristic, but if you angle you hand in the way you need to in order to hold this level, it'll strain your hand into a poor firing position. Granted, for a video game, that doesn't matter as much as if you were planning on making it in the real world, all the same, maybe a reduction in the grip angle and a different magazine.
Aside from the handle and magazine, looks cool, can't wait to see the game it's going into.