Goblin Attack

Goblin Attack sticks to classic tower defense fundamentals, place towers, upgrade them, survive escalating waves, but keeps its single enemy type, goblins, varied enough in speed and numbers that the strategy shifts noticeably from one wave to the next rather than repeating the same defense forever.

Early waves are worth using to scout goblin pathing and place cheap towers along choke points rather than investing everything into one heavily upgraded tower, a wide spread of coverage tends to handle a sudden rush better than a single powerful tower with gaps on either side. Saving upgrade currency for a defensive gap revealed by a near-miss wave usually pays off more than maxing out towers that already comfortably handle their section. Crown Guard runs a similar tower-defense structure with a wider roster of unit types to mix and match.