Assault Android Cactus is easily one of the absolute best indie twin-stick shooters around and it's now bigger and better again. Note: My key was originally from a PR team years ago.
Just today, Witch Beam released the Assault Android Cactus+ update which includes a new Campaign+ game mode. This newer mode, originally in the Nintendo Switch version mixes the gameplay up something fierce, giving you a fresh challenge with rebuilt stages and new enemy waves along with "amped up boss fights".
Also, if you previously found the game too difficult, there's a new Automatic Aim option found in the Main Menu under Accessibility Options. This allows you to worry about the action, without needing precise aim and saving your thumb a little. I've tested it and it works very well, making it a smoother experience and likely a lot better for a younger audience now too. Since it's an option, it doesn't change anything for experienced players or anyone looking for a challenge.
If you've never seen or played it, I honestly think you're missing out. Have a look at their original trailer below for what to expect:
Other changes that came along with this update include a Movie Gallery, new Android costumes, you can now hold a button to revive when knocked down but it's slower than tapping, along with a Revive Assist accessibility option. They did also note "Too many fixes, improvements and adjustments to list" so overall it should be a smoother game.
The Linux version, as tested today on Ubuntu 19.04 continues to run beautifully.