u/F-Radiation

Gameplay: Objective is to gradually take over a map made up of hexagonal zones. You start with 1 zone and can then enter a neighbouring hostile zone which will put you into a 3D environment. You face a wall that zombies come from (memory is hazy, they either walk through or climb over the wall). Actual defence is a third person shooter with a variety of weapons (Rifles, shotguns, pistols, etc.).

From the map, you can also purchase and upgrade allies (Colonel, Private, Sergeant, Guard..?) each with a set of stats and how they help you. Colonel had high damage output wielding a rocket launcher, Guard was melee with poor damage output but had extremely high scaling health and defence with upgrades (also cheap and so you could deploy lots), Privates and Sergeants wielded rifles with more balanced stats and costs. (This system I can remember more clearly because it really stood out to me how many allies you could deploy and how high thier stats scaled if you poured all your currency to upgrading one ally type.)

Map was entirely red starting out, zones owned by the player were blue indicating they were friendly. I believe there was a system where friendly zones generated resources and you had to sometimes defend zones that were at risk of getting turned red from being attacked.

Graphics: Quality wasn't great, used somewhat crude and standard models for all the units. Normal 2D UI when not in combat, 3D when in combat. Not really cartoony, more gritty.

I estimated it released early to mid 2010s but that's closer to when I played it. Actual release date might be earlier

In light of Middle Outis being a little silly with it

[Mobile] [Early-Mid 2010s] Zombie game where you gradually take over a map by defending from a wave of zombies, with the ability to prepare and upgrade allies before entering a zone;