(First review on NG ever, hopefully I won't screw something up...)
I can definitely see your improvements here. From the first one... well, I don't need to say anything. From the second one, there was definitely more resistance from the agents, which is something I definitely wished the previous iterations had more of, and I like that. So, solid work on the action and gunplay there. There were some times midway through where I think sounds were getting out of sync, but my hard drive needs to be replaced, so that might just be on my end...
The voice acting was also well done here. I definitely laughed at the first part all because of it and having it in the combat scenes didn't really slow it down. The voice quality was also on par, so props to all of the actors.
Now the ending... yeah... problems. It seemed like it was going to be good, but I started feeling suspicious when Sheldon's ally (that dude in the green shirt, was he supposed to be his dead friend? I didn't see him in the bios) was just one-shot but simply ignored. Then Sheldon just wipes out the sheriff in just a few seconds and that's it? It was just so anticlimactic, man! It feels like after six and a half years you just wanted this to be done and out of the way.
But overall, it's clear your animation skills have improved greatly over all three Madness Hunts. You still end this story on a high note. (P.S. If you need voice acting for future animations, feel free to PM me, I could definitely lend a hand ;) )