Question: Is there a web-based game engine that allows real-time collaboration and editing, and can publish games to multiple platforms?

If you're looking for a web-based game engine that supports real-time collaboration and editing, and lets you publish to multiple platforms, Dreamlab is a top contender. This engine is geared for fast development of multiplayer games with modern web technology. It's got real-time multiplayer support, AI-generated assets, and support for JavaScript and TypeScript programming. Dreamlab also offers web-based development, real-time collaboration, and the ability to publish games as standalone web apps or Discord Activities.

Another top contender is Photon Engine, a cross-platform multiplayer game backend service. It can run on Android, iOS, .NET, Unity and other platforms. Photon Engine has advanced state synchronization, high performance and a variety of features for real-time multiplayer games. It also has a flexible pricing plan with a free tier, so it's available to developers large and small.

Azure PlayFab is another good option for building and operating live games on multiple platforms. It's a suite of services that includes multiplayer support, real-time analytics, data storage and compliance. With flexible pricing and a free development mode, Azure PlayFab is geared for developers of all sizes who want to build and operate live games.

For real-time digital experiences, Ably offers a variety of APIs for building apps with live chat, data broadcasting, data synchronization and multiplayer collaboration. It has more than 25 client and server libraries and offers reliable and scalable options with high uptime and strong data integrity. Ably is used in a variety of industries, including EdTech and FinTech, and offers a free tier with upgrade options for heavier usage.