Infested Planet is essentially a tactical RTS, but without the messy resources and busy manufacturing queues. As commander of space marines, you are tasked to wipe out whatever baddies you come across, and these guys adapt to your tactics, and will throw you quite a few surprises. Think of it more as a puzzle, than a straight combat game, and you should have fun.
The graphics are fairly minimal overhead view without fancy-shmancy 3D options. No rotation, just scrolling. The idea is simple: start with one "base" area, and you need to beat back the alien horde with your marines and maybe some sentry turrets, but you need RPs (resource points) to build them, and you can also use RPs to buy enhancements for your teams, such as medical pods (healing), grenades, shotgun upgrades, minefields, officers, and so on. Some are semi-permanent, others are single-use buffs only. RPs can only be earned by killing alien hives.
So basically the trick is build the right stuff at the right time. if your marines got killed, replacements are sent down to the nearest conquered "point". Your marines also have some heavy weapons (think RPGs) that can be used to kill individual units. If you find some "metal" you can have it dragged back to the control points where it is added to your RPs. You can also find ammo crate which gives you back your "ammo" (for heavy weapons) immediately rather than wait for it to SLOWLY regenerate.
As you beat up aliens, you unlock more toys to play with, such as extra med pods, shotgun, minigun, extra marines, officers, etc. But obviously, the alien horde gets better too. First it's just swarm, then alien hives gets "gunners", then they can generate their own "marines", mines, mini-spawn nodes, hive artillery, speed rush... and more. You can play either story missions or "raid" missions. Story missions advances the plot, while raid missions just earns you money that lets you unlock even more toys.
So the key is build just enough to help you take out one hive at a time and build defenses to hold the points, but there's a lot of different ways to do it... Do you blitz the hive and accept casualties, or do the turret leapfrog, i.e. build turrets to cover each other and advance slowly but surely?
I've went through a dozen missions by now and there's two dozen more to go, and there are weekly challenges, and there's some updates coming soon. You can repeat the "raid" missions to earn more money for the goodies.
All in all the game is a lot of alien blasting fun as you groan at loss of each marine and cheer when you take out each hive. The game may not be flashy, but it is a lot of fun. Highly recommended.