Hey, pretty cool stuff here! Overall the game has a really polished and refined feel to it: everything felt really smooth, I liked the look of the art/animations, the sound effects and atmosphere were cool, and the neat touches like providing hints on the game over screens and hidden references and so on were great. Also I really appreciate that, despite being an April Fool's game where most people would just treat it as a joke, this actually had some serious effort put into its construction! I could certainly dock some points to this for just being yet another FNAF clone with a Henry Stickmin paintjob, but I had a good time so I can't fault it too much.
I have beaten the game now and had a short but sweet time with it (and enjoyed the Extras as well), but there were some tricky parts to learn at first, especially since I've never actually played FNAF before, and some annoyances with the game that I had to contend with.
*I wish the whole 'securing power terminals' was a bit more eye-catching as I wasn't even aware of its existence for quite some time, and I also wish it provided a bit more feedback when you turn it on since I wasn't sure how it worked, like perhaps having the power terminal shown on camera have its buttons change color or even have an animation of it slamming shut like the doors do or shocking whatever Stickmin messes with it. In a similar vein, it'd be nice if securing the vents would also have a graphical change that can be seen through the cameras as feedback.
*While merely hovering around the boxes to change views/interact is smooth and does reduce clicks, I sometimes wish it would require clicks as confirmation instead as I'd have some strange misinputs at times due to unintentionally hovering over a button. Sometimes I'd have the cameras flip up only to immediately flip back down due to the game thinking I hovered over the button again, for example. But worst of all was that I had one annoying death where I had a Stickmin at the door and went to close it, but my mouse grazed past the reboot monitor button which flipped it on and allowed the Stickmin to get in and kill me: argh!
Again, nice work with this!