Building a Gacha Tower Defense in Cocos Creator: Wave System, Merge Logic, and 28 Enemy Types

I wrote recently about migrating from LayaAir to Cocos Creator. This post is the follow-up: what I actually built with Cocos after the migration settled. The game is Cosmic Summon, a gacha merge tower defense. Players summon heroes randomly, place them on a grid, and combine duplicates to evolve them through seven rarity tiers. Enemies spawn in 50 waves themed around real constellations. Bosses appear every five waves. This post walks through the technical decisions behind three of the core syst