I went a bit "download happy" on shoot'em ups this weekend. So here's a few that actually ended up OK. I've never even looked at them before due to their crap names, or that they're new, but they're all not bad. They're mostly retro'y or voxel'y graphics wise, but they're all nice in that they offer instant gratification but with long-term upgrades available. Also all with plenty of free options to just try stuff out. I hate leveling pointlessly. Just give me the death rays early, so you can make it hard but fun....
Galaxy Bug is essentially Galaga. Or more like Galaga '90, in that there's plenty of weapon options available and a boss every five levels. And I love me some Galaga. Can get missiles on your main ship/wingmen, or split shot for the incompetent at aiming (which I am). Seems pretty generous in that I have a lvl5 legendary split shot ship, and wingmen, in under 24hrs. It's like you've got the mega weapon lite going all the time. Anyway, it's good. Only up to lvl25 so far, but I haven't played that much. Anyway, it's staying on my phone forever.....
(you can scroll the shop items horizontally, so there's heaps of stuff to buy. Grind past game level 20, and get a legendary ship of whatever weapon type you like. Saves pouring credits into something crap)
Nice in that you can scale yourself way back for a more "pure" experience if you want, or go flat multi-everything from the word go. They give you all the options. Even p2w ones, that truthfully, I may use at some point. But you get one of each ship, wing man, and plenty of gubbins to try out, which in my opinion makes it a good shooter (I tend to judge shooters by the "Tyrian" standard, not the "requires skill" standard). It's Galaga, but it's fun.
Noah [DANMAKU shooting] is an artsy bullet hell, that isn't really that hellish. Nice aesthetic, and a fair few ship upgrade options. Haven't really sunk my teeth into it yet. Still, if you like something a bit more abstract, this is a good one. It also has the advantage that it's a Japanese game, so you get to watch all the bullshit awesome jap game ads at the end of a playthrough (honestly, it's worthwhile downloading just for this. Everything in-game is easy to understand, even if the graphics are LSD'ish abstract lineart, and then afterwards the ads are just a weird added trip-out to bring you back to "reality"). You will want some more nice, calming 60's style LSD straight afterwards.....
Are you addicted to the surrealism, or what's in the box? You know you're going to click the box anyway, so you may as well come into it in the right frame of mind.
Pixel Craft is, umm, a retro shooter. Kind of. It's more like a modern shooter, but with purposely coarse graphics. Plenty of powerups, and actually quite good looking in its own way. Plays rather well. Only tried two ships, but no doubt there's plenty of play there. It even has the ShooMachi -shipsize thing available, which makes me think it might be good. I'll have to play more to see.
Retro Shooting is a voxel'y shooter, with a nice array of ships to choose from, and a constant stream of powerups chucked at you each level. Think Raiden, but with voxels, and you'll have your missiles and max firepower before half the level is over (each level is a thing to its own, but they throw available firepower at you straight away) . Nice, well defined bullets and powerups, so you'll never confuse one for the other. Again, plays well, and gives you enough instant gratification to make you want to burn through another level.
These are all some of the better shooters I've played recently. Honestly, I've trawled through some absolute crap over the years, with either stupid business models or just plain bad gameplay. These are all average-good, leaning towards good-great. Plus, they're all pretty much free, if you don't mind watching a few ads.
There's also a few good diablo-likes and action roguelites that are new, but I'll wait a bit to bother posting them, because they may deserve a more thorough run down.