The multiplayer is way better than singleplayer but unfortunately there is only local co-op.
+ While this game looks like any other shoot-em-up, it actually has a few ideas that make it unique. One of the main things that makes this game enjoyable is that you have a very small hitbox for your avatar. Meaning that bullets can go through the side of the ship but if they touch the very center then you'll explode. This gives you a big margin for error, allowing you to weave around on screen. And while it may seem like this is too easy, there will soon be tons of enemy projectiles floating around on the screen and you will have to maneuver through some very tiny gaps so it actually is fairly balanced. The other thing to remember is that one hit will destroy your ship. In single player this means you have separate heart icons that count how many times you can respawn before you use a continue. In multiplayer this means that you either have to wait an allotted amount of time before you respawn (typically 8 seconds) or one of your friends can try and find a respawn powerup which will instantly revive you.
The other thing that makes this game special is the Vaunt ability. Every enemy you kill drops golden rings. If you collect these then they will fill your Vaunt meter. Once your Vaunt meter is full you can press a button which will immediately generate a shield around you which will provide you invulnerability for you and any of your allies within the vicinity for a second or two. This is extremely important and necessary in the later levels and serves as an "oh s#@t" button when there is just way too much on the screen and you need to protect yourself. As soon as you use it then you will gain a points multiplier and your Vaunt meter will begin to drain. The multiplier lasts until your Vaunt meter is entirely drained, but grabbing more rings will keep the meter boosted. While your Vaunt meter is depleting you do have the option to use a mini-Vaunt which serves as an "no really...oh s#@t" escape. It's a smaller sphere and it doesn't last as long but it will protect you for a very short time, as well as completely depleting your Vaunt meter. Once you've understood how it works, the Vaunt ability is one of the key elements of the game and you really must use it at the right moment in order to fully capitalize on it.
There are four types of gunner ships available for you to choose from, each with their own special ability. The problem here is that in single-player you really can only afford to use the default ship because it's the best all-around. So you can't really get the full experience this way. But the game is clearly meant to be played with a group of friends, and by doing so then you can choose different ships that balance each other's strengths and weaknesses. Again, it is unfortunately but the only way you are able to play multiplayer is locally (there is no online co-op), so you'll need extra mice+keyboard combos, extra controllers, and extra friends. But after playing both modes I can definitely say that multiplayer is leagues ahead of singleplayer in terms of how fun it is.
There are five main levels in the game. Each has a range of difficulties you can play it on (about 5 for most level, though the hardest ones you have to unlock). The first four levels are somewhat short and the bosses are not that challenging. But once you start playing on a higher difficulty you begin to realize how tricky it can be. And you will need to play the higher difficulties because in order to unlock later levels you will have to beat previous levels at a higher difficulty. This may be annoying for some, but there's no way around it. The final level and final boss is both long and a real tough challenge, and you'll have to play the level quite a few times before you understand the perfect path to make it to the end with all your continues.
Beating each level will earn your money, which is then used to purchase stuff in the store. These include new ships, new difficulties, and new challenge maps. The challenges provide specific goals that you aim to achieve, such as surviving for a certain time length, moving through rings on the map while staying alive, getting a high score, or navigating through a maze. They can be pretty challenging at times, but they do offer some diversity since there aren't many main levels in the game. There is also a gauntlet mode which lets you play through all the main levels in one go-through.
Overall you may find that the single-player is a bit lacking, which is fair to say. The game is fun though and does have some unique features that make it appealing. But there's no denying that the game is intended to be played with a group of friends nearby, and you won't get the real experience unless you try it this way.
Story/Presentation: 3/5
+ The story is goofy and absurd in an interesting way. It mixes historical elements with sci-fi. You are from the revolutionary time in America and the colony of Jamestown, but that colony is now on Mars and you must use your space ship to fight evil machines. It's bizarre but definitely original. There are only a few cutscenes that explain what's going on, and to be fair the story text can be glossed over and you won't be missing much. But I did like how inane the premise of the situation was and there's no denying its originality.
Graphics: 4/5
+ The graphics are from an era gone by, but to me that is pleasing. So the graphics are technically advanced, but the aesthetics and colors are definitely pleasing. The levels, ships, effects, and enemies all have a beautifully defined color palette. At times things get crazy and there is a lot of stuff flying around the screen, but you're still able to see everything. But if you love good pixel art then you should definitely be pleased with what this game has to offer.
Value: 3.5/5
+ I played the game for about 7 hours with my friend. We beat all the levels including the final boss, and we beat about 14 challenges. There were still some challenges that we left unfinished, as well as some levels which we didn't complete all the difficulties with. But by the time we stopped it felt like we experienced enough of the game. If you are a completionist then there are a number of things available for you to finish, but the higher difficulties and the challenges do prove to be pretty hard to complete so you may waste a lot of time trying to finish them. The price of $10 may be slightly high especially if you're mildly interested in this game. It is fun, but as I've said plenty of times before: you really only get to experience it when you play multiplayer. So if you're looking for a fun new sh'mup and you have a group of friends then this game is surely worth the price. But if you just plan on playing single player then you may want to wait for a sale and then decide for yourself whether it's worth it.