TL;DR: Retro-styled in looks, sound, and difficulty, this sidescrolling run-and-gun platformer with some shmup stages will slap you around a bit, but will still play fair.
I'll preface this by saying I got this in the Groupees Be Mine 11 bundle. And this is probably the first time I've gotten a game, downloaded it, played it, AND beat it all in the span of maybe a couple of days. So with that said...
Ultionus is the story of a woman, her robot head partner, and a social networking comment that leads to a crash landing and a lot of things to kill. As you can tell by the screenshots, it's a "retraux" game, a modern game made with retro-inspired graphics and gameplay. You actually don't have a gun at the very start, so you need to rely on your bouncing robot head partner to destroy the enemies as you move to the left, and then you get a gun and can start blasting everything to death. This threw me off at first, but that's what experimentation is for, right?
I thought this game was pretty hard on Normal, but it wasn't unfair about it. Our heroine can only take so many hits before she explodes in a shower of cartoon hearts and respawns at the last checkpoint or stage entrance. You get restored to full health when you pass a checkpoint the first time or find a red heart 1UP. Controls are fairly tight, though Serena is a little slow on the ground and especially while firing since she stops altogether. You'll be spending most of your time in the air, and thankfully this game doesn't fall into "Castlevania 1 jumping" where you can't change directions mid-air. Hitboxes seemed pretty accurate and there aren't really any fancy controls. For the 360 controller, A could be tapped or held to change the height you jump, X and B fire your ray gun, Y doesn't seem to do anything, and the d-pad and stick both can be used for movement. No movement faster than a leisurely walk, no sliding, no wall-jumping...simple stuff.
There are upgrades, but you not only have to find a special coin in each level, but also get to the merchant's door. I'd also add "and have enough money to buy the upgrades" but you get money by killing everything you see, and you'll be doing that anyway. You have to choose between offense and defense, and you can only pick one per stage. If you find the coin and door that is. There are multiple routes through each normal platforming stage, and the auto-scrolling vehicle ones obviously only have one route. Get to the end of the level and you fight a giant enemy thing. Die and you start the fight all over again. Learn the boss patterns or you'll eat through your stock of lives (on Normal and Hardcore; Easy gives you infinite).
I would honestly suggest trying this on Easy first. It takes the pressure off of playing well and it'll allow you to go through stages by different routes and learn boss routines, even though running out of lives merely gives you a prompt to start the level over with 9 lives and all of your money, or exit the game. I started on Normal, and I honestly game overed twice, though I didn't get the best ending (the bad ending spells out what you need to do to avert it though). The dev has said on the Steam forum that playing on harder difficulties will unlock achievements for that and the difficulty level(s) below it. So if you get the best ending on Normal, you get the Easy achievement too, for example. There aren't many achievements but they're actually something to work towards. Without trying, I got two for winning on Normal with the bad ending and watching the credits all the way through.
Graphics are really colorful and the animations are quite nice. You can pretty easily tell what would hurt you and what won't, and there's quite a bit of detail work done here. You don't really notice the big border after a while. I didn't really feel like I'd do better if I didn't see it at all. The music's pretty catchy and I kinda wish there was a sound test option (or maybe there is one and I just haven't unlocked it yet). I don't really have much to say about the sound effects. They're there.
I won't do my usual "I liked/disliked this" sections since there's not much to say. I had fun. My heart raced, I cursed, and I'm not only glad this is on Steam, but I'm glad I gave this game a chance. It's short, but there's a little bit of replay value, and I can see myself giving this game a few more hours. I've forgotten what it's like to actually have
to learn patterns and get penalized by starting boss fights over when I don't.