INTRUSION 2 is a 2D run n' gun action platformer along the lines of Metal Slug or more vaguely Contra. This is one badass, fun game, with epic, memorable bosses and creative elements like some pretty basic physics and destruction. You can destroy log bridges to send everyone falling to their doom, blow up the supports of watchtowers. Crush enemies under boulders you push over. Physics like that, which add to the fun. The enemies can take a beating and the weapons feel good, but even if there is a variety of weapons, not many feel different from one another. The levels seem like a marathon. They are so long you might find yourself wondering when they end. This is probably good.
Earlier I mentioned epic bosses. I don't use that term lightly. It makes me feel weird, but let me tell you about the first boss, a helicopter or hovercraft with arms with multiple phases. If its not shooting at you, its dropping soldiers out. If its not trying to hand pound you into the ground, its literally crawling after you. Its insane and awesome. It is very memorable and covers a lot of ground.
To keep things fresh, you can pilot mech suits... if not grab the gun off of a destroyed mech and use it on your enemies. Oh and if that's too normal for you, in the first level, you can ride a giant Arctic wolf. Its pretty nice.
The game is challenging, you do have a health bar, and ammo depletes, and you can die more from the controls than you do anything else, BUT the game is very forgiving, with plenty of checkpoints.
The controls take a bit of getting use to. You have your standard jump, duck and weapon switch keys, but then to aim you use your mouse. This allows for more precise aim, but I'm more used to the Contra controls of having 8 direction shooting instead of precision. If you're used to Teraria, you'll be used to this. There is floaty jumping that can take some getting used to and the physics seem really light and springy. The boxes will bounce around if lightly nudged. Some of the animation is springy like old cartoon characters. That is probably Flash animation for you.
It took a while to get over it, but when I did, I found this game to be really fun to play. There are crazy Holy ♥♥♥♥ moments, and moments where the physics can have some unique experiences for a 2D run n gun game, such as seeing a mech jump onto a floating box. The box bounced the mech up and kinda floated away just enough for a giant fish to eat the mech. That wasn't supposed to happen, but it did, and it was cool.
Well worth $10.