RAIDEN-Sky Force Ace is a new vertical shoot 'em up from LeTang Inc. LeTang is a China-based game company (at least I think they're Chinese, don't quote me), and all their recent titles have been simultaneously released in Chinese and English. This game makes use of fantastic retro sprites and chip tunes, decent gameplay, and absolutely hilarious translation errors to create something kind of magical.
After booting the app up and starting a new game, you'll choose between three different pilots and several secondary weapons before heading into the tutorial. There is quite the variety to choose from. You control the ship by dragging it around the screen as it automatically fires up at the descending enemies. As you destroy them and collect the crystals that they drop, you'll eventually level up your ship to have stronger cannons and what not. The game is very linear and unfortunately there are no separate save slots, so starting a new game will wipe your progress. There are no mid-level checkpoints either. It can be really frustrating to die on a boss after a fairly long level just to start over from the beginning.
The gameplay is pretty simple, as you can see. The controls can be a bit unresponsive and the game can be a bit choppy at times. It isn't really all that compelling to be honest. What makes the game fun to play is the absolutely terribly translated story. I mean, this is "All your base are belong to us" quality bad, and the game had me laughing constantly. The pixel art graphics and old-school sounds and music are all very enjoyable. Some people are having troubles with push advertisements, and this game is honestly quite weak both technically and when it comes to design. I probably wouldn't flat out recommend a game like this normally, but considering that it's totally free, you should definitely give it a shot. It's great silly fun.