The only really weird thing is the cylinder. It looks like you took the cylinder from a Navy model black powered revolver and matted over it with a cut down cylinder from a Single Action Army? In most other respects, it's a pretty good technical design. But, especially if you're going with a cartage revolver, the cylinder doesn't seem to do anything other than leave the back open to fire a jet of hot gas at the wielder. If you replaced the cylinder you have now with a full sized one from, say, the Single Action Army I mentioned earlier you'd have something that would actually be pretty much technically correct.
I realize that it's not intended to be an entirely accurate weapon. But for a video game use, it could be a small change that'd be very useful for that extra little bit of veritas.
Otherwise, this is a very interesting design. It obviously draws inspiration from existing revolvers of the period, but it doesn't fall over that line into being just a Navy model with some parts glued on. You've got a good design that just has one part that's rather jarring to look at. If you fix that, you should have an awesome piece (aha).
I agree with what Savayan said,perhaps extending the cylinder so that it reaches the hammer and could maybe accept a larger caliber. How is the break operated,there doesn't seems to be a lever of release for the barrel and cylinder. Maybe adding a little lever just under the hinge to release it,or even that flashy grip could extend to the hinge and be pulled down to release it. Also i'm wondering what the ram rod is functional as.I know that when cartridges were introduced many black powder revolvers were converted but the ram rod was removed and replaced with a shell ejector. But over all i love the design of this revolver,it seems very post apocalyptic western (flashy and gritty.)