A strategy/tactics game with nice graphics, decent story, and somewhat stereotypical characters and situations representing various countries. If you're not willing to grind out old maps for gold, then this game isn't for you because replaying maps for gold is pretty much mandatory to make later enemies easier. If you're not good at tactics games or don't like taking things slowly, this game isn't for you because there are enemies that can easily kill your characters if you aren't prepared because they have enough Action Points to move large distances and shoot many times.
Right now I'm up to the third campaign, Morning Star (if you include the first tutorial campaign).
The english in the beginning is pretty awkward and poorly translated, but it gets a lot better later on. There are still some mistakes/oddities ('Eliminate the elite forces. None of the squad should not perish.' and 'Above the rate of fire!'), but the dialogue between characters is acceptable.
After the tutorial maps, losing a map after clearing some enemies nets you ~3-10k gold, while clearing a map gives ~25-40k. The costlier upgrades cost ~27k-40k and opening the tier 2 reward boxes requires ~15k each. You will probably want to clear Normal stages first and ignore higher difficulties until you upgrade your characters enough. Since you don't get much gold, try to concentrate your gold on upgrading a couple core characters that you use (upgrading Teddy's Guard Ability to grant 2 shields is pretty useful). Buying items can save your run, but they cost a lot of gold which (in the long run) is better spent on permanent upgrades. You have to take things slowly and carefully, use Guard right before an encounter to absorb any fire they get in, and try to disable anyone you can't finish off.
Edit: Beat all stages I own in the Antisquad Original on hardest difficulty and cleared all stages I own in Antisquad Tactics. All the missions I had in Tactics were tutorial-like, so you might as well play through those before playing the original game. It plays pretty much the same but everything is cheaper, characters have less upgrade tiers, and the stages are a lot easier (at least on normal difficulty). The two versions don't share anything (gold, items, etc.).
In Original, I found a small stage that gave decent gold that I could clear quickly and easily. I ground that level for gold for key upgrades until I could beat it on higher difficulty levels (it gave ~60k normal, ~130k highest difficulty). After that, levels were mostly a cakewalk. You unlock new weapons and armor to buy when you upgrade your character's stats enough to increase their rank. It can be very effective to increase damage through a better weapon and start with more armor from a better outfit.