Multiplatform Open-World Roleplay Game

I’m building a fully-featured, open-world role-play experience set in a believable city that players on PC, console and mobile can explore together in real time. The map will contain distinct neighborhoods and purchasable or rentable housing, all rendered in a realistic style with day–night and weather cycles.

Core gameplay revolves around a job system: police, firefighter, taxi driver, courier/delivery and any further roles we later add. Each job must include its own vehicles (cars, trucks, emergency units, etc.), tools and branching task logic, all tied to an in-game money and economy loop so players can earn, spend and trade.

To support immersion I need:
• An account-based multiplayer framework able to handle large concurrent populations, party-based voice/text chat and authoritative server-side anti-cheat.
• A character creator with custom skins, wardrobes and accessories that sync across platforms.
• A modular UI: job selection, inventory, interactive 3-D map with GPS routing, settings and social panels.
• An in-game admin dashboard where moderators can kick/ban, move, spectate or message players and tweak job payouts or spawn rules on the fly.

I’m open to Unity, Unreal Engine or a comparable stack as long as cross-platform builds remain performant. Code must be well-commented, network-safe and handed over with clear documentation, build instructions and a short gameplay video that proves:
1. Seamless connection of at least 10 simultaneous players on each target platform.
2. Working police and taxi job loops (accept mission → complete objective → receive pay).
3. Property purchase, storage access and a basic economy transaction.
4. Admin panel functions executed in-game without downtime.

If you already have reusable systems, plugins or server infrastructure that speed up delivery, highlight them when you respond—I’m happy to license proven tech.