BioGun is a fun Metroidvania brimming with charm.

The world of the game has you exploring the inside of the body of a dog in order to save it from a virus. All areas, enemies and characters are themed according to this in a very imaginative way. All of the doggie aesthetic makes for a lot of lovely and cute experiences, while the reality of the effects of the virus can contrast with some grim realities. Either way, the visuals are beautiful.

The gameplay is a lot of fun. Most of the controls are re-mappable. I played with the bumper-jumper control set (I swapped the triggers with the bumpers), since I wanted the extra accuracy of the twin-stick combat. This took some getting used to, since I don't think I've played bumper-jumper style before, but I adapted quickly and mastered exploring the world. Combat is responsive and you can maneuver around the enemies adeptly once you learn how they move.

In terms of difficulty, I'd put it around "medium". A seasoned metroidvania gamer might need a round or two to learn a boss's moves, but should be able to dispatch them once they do. Others might find the rapid reactions necessary to be more difficult. There are also weapons in the game which are directly an invitation to challenge yourself, so you can always do that if you want to turn up the heat.

Searching for secrets is very accessible. False walls are, as far as I could tell, always visible to the eagle-eyed player, but easy to miss if you're not paying attention. Even if you don't see them, the twin-stick shooter nature allows you to test them all quickly with your gun. On top of that, a thorough explorer (or someone willing to farm for currency) can use items to upgrade the maps of each area to label where to find secrets, to save you the "where did I see that thing I couldn't get earlier" endless backtracking that tends to happen in action-adventure games. Besides that, there are map pins to help you mark places of interest for later.

There are a lot of optional collectables (hello hats and masks), upgrades and bosses for completionists.

That was a lot of positives; how about some negatives? There are some bugs, particularly in the UI (at one point my save file said I was INFINITE% complete :D), but I didn't encounter any that were serious. The dev is actively patching things, so those should diminish with time. The main issue I encountered in my playthrough was frame rate drops. These may vary from user to user, based on other reviews. For me, they were noticeable, but nothing that ruined my fun. Hopefully these will be wrinkled out in future patches as well.

EDIT (2024-09-29): I was recording my original playthrough, but I've since noticed that when I'm not recording, the framerate issues are noticeably reduced and loadtimes are also shorter.

Over all, I would highly recommend this game, especially for action-adventure / metroidvania fans. It is clear that a lot of love went into creating this game. This is a world that deserves to be explored, and you owe it to yourself to explore it. Have fun!