This game is freaking epic! You can choose from 4 players, one uses a assault rifle, another is a sniper, and so on. They each have their quirks and you can equip two guns at first more after that. I adore tower defence games and this allows you to place towers and upgrade with guns etc. The playing field is a grid you can build your maze on. Then add in the FPS part. You lay out your towers each turn and then there is a lull, it gives you a limited time to place the towers but there is enough easily. Then it starts. The aliens will go for you but you can hop on top of the towers or buildings around the area. You are in a limited area but you can go off exploring in buildings/parks and maybe find a bonus or two. Being able to actually defend the objects yourself by slaughtering aliens is awesome. Use the shotgun and you can literally blast them into pieces hehe 😀
It was on humble bundle so unsure of the price on Steam but well worth it if you like Tower Defence and FPS!