This app was mentioned in 3 comments, with an average of 3.33 upvotes
Pixel Fodder: https://play.google.com/store/apps/details?id=air.com.wacha.pixelfodder
A portable little BROFORCE sandbox clone where you play (or create) from a wide list of badasses. The game has plenty of levels and lots of shooting to be had. There's also both a Level Editor AND a Random Area Generator. And the character creator has a lot to choose from.
Pixel Clash RTS: https://play.google.com/store/apps/details?id=digitalbarbarian.rts
A simplistic but surprisingly deep RTS-like game with 5 playable factions. Each faction plays very differently from the other. The game can get to a full scale RTS conflict for less than a minute. Terrain consists of blocks that might fall off the map sending units and structures into their oblivion (though some can hover to prevent this).
Army Of Pixels: https://play.google.com/store/apps/details?id=com.hydragraphics.armyofpixels
A well made Lane Defense Strategy game that mixes Turn Based Strategy by preparing what units to send off to the enemy's army and ways to counteract a recent conflict. I can personally feel a sort of CCG element at how you can purchase other factions (They're not very expensive anyway, just win on any mode 4 times and you have enough money to buy one). Enemy AI isn't the best atm but the game is surprisingly fleshed out...it being free is almost too good!!
Barrier - https://play.google.com/store/apps/details?id=null.noclip.barrier
A high speed Macross Simulator where you play as a ship going through obstacles and shooting enemies with your awesome looking guided missiles. Since its a paid game you can try it on your PC right here.
http://winesays.itch.io/barrier
Robot Dangerous: https://play.google.com/store/apps/details?id=digitalbarbarian.robot
A time based RPG reliant on your reflexes and long term decision making. You play as a robot exploring the slums of a dystopian future in an attempt to fend off the many gangs and criminal scum with a wide variety of weapons at your disposal. Your weapons/skills run out of ammo and you don't get to replenish them until the end of the level (where one charge of ANY skill costs 2 dollars). So use your time and money wisely...because there's permadeath; but there's also a Save & Exit option...already making it better than most of his other games.
> "Pixel Fodder" is a classic 8-bit platformer with a destructible world, large choice of characters and incredible dynamics. Use all the pixel force to eliminate the bad guys! Fight for scientists, warriors, zombies and other to save the world! Or just destroy everything in a quick game mode :) — http://wacha.itch.io/pixel-fodder
https://www.youtube.com/watch?v=2vb7hNE8qK4
The game is available for Windows & OSX, uses Adobe Air (same download for both platforms - but you need Air installed to installed the game).
Also available for Android on the Google Play Store, separately (purchasing on itch.io won't give you an Android version, and vice versa). Actually there are a bunch of reviews there you might be interested in, since it's the same game as far as I can tell.