sandbox game, physics-based interactions, multiplayer, creative freedom, prop manipulation, character customization, user-generated content, modding community, Steam Workshop, Half-Life 2 assets, role-playing servers, puzzle-solving, game modes, map editor, Lua scripting, dynamic lighting, ragdoll physics, construct mode, face poser tool, wiremod, NPC interactions, custom vehicles, game integration, first-person perspective, interactive environments, comedy elements, emergent gameplay, cross-platform multiplayer, Source engine, physics gun, tool gun, community servers, addon creation, collaborative gameplay, virtual playground.