Roblox game architecture

The model in one paragraph

Every Roblox game is a server (authoritative, runs Scripts, sees everything, owns DataStores) plus one client per player (runs LocalScripts / client Scripts, renders, reads input). The server's DataModel replicates to clients automatically. Client changes do not replicate back, except: physics of parts the client has network ownership of (its character by default), its own Humanoid state/animations, and remote calls. Assume every client is compromised (see roblox-security). Design every feature as: client requests → server validates and decides → state replicates → clients render.

Where things go