Plant Squad

Plant Squad is lane defence against a zombie advance, with one mechanic layered on that changes how you spend: you can merge plants. Two of the same kind combine into something stronger, so every plant you place is both a defender now and a component later. That turns the usual question of tower defence — can I afford the better unit — into a different one: can I afford to hold a weak plant in a useful lane long enough to merge it. The zombies do not wait for you to finish arranging things, which is the whole tension.

Zombies advance along lanes toward you. Place plants to stop them, and combine two matching plants to produce a stronger one. Clear every zombie in a level to move on. Because merging consumes two units, the board is always a trade-off between having enough defenders right now and building toward something that can handle what is coming.

Merge early rather than late. A merged plant in wave three is worth far more than two unmerged ones in wave six, because the stronger unit compounds every wave it survives. Keep your merging happening in the safest lane — doing it in the lane that is under pressure means you briefly have one fewer defender exactly where you need two. Do not spread evenly across all lanes; zombies come in pushes, and a strong lane that holds is better than four that each nearly hold. And watch which lane is emptiest before each wave, because that is where the next push will hurt.