Question: Is there a service that offers a marketplace for purchasing and customizing 3D assets, and also provides an SDK for integrating character creation into my game engine?

If you want a service that offers a marketplace for buying and customizing 3D assets and an SDK to build character creation into your game engine, 3DAiLY could be a good fit. The service lets you create characters with a Gen AI-powered character editor and offers a marketplace to buy lots of assets. You can also order custom assets and build the SDK into your games for avatar creation and asset management. Subscriptions range from a free trial to basic ($9.99/month), pro ($39.99/month) and enterprise ($99.99/month).

Another option is Sloyd, an AI-powered 3D model generator that lets you create detailed models with text prompts and that offers a large library of procedural assets. It also offers an SDK for real-time 3D creation in games or apps, including Unity. The system comes in three tiers: free Starter, $15/month Plus and custom pricing for Studio & Enterprise, so it's adaptable to different levels of development.

If you're looking for a more specialized avatar creation service, Ready Player Me offers a premium avatar system with thousands of options that can be customized. It's designed to plug into popular game engines like Unity and Unreal, using open-source SDKs. The service's Developer Studio offers a lot of control and customization, and it offers tools to monetize hero avatars and skins. That could be useful for social experiences, virtual meeting tools and games.

Last is Tafi, a 3D content creation platform with a Text-to-3D AI character engine and a library of assets. It also offers dynamic 3D character solutions and custom character services. The service can be integrated with big game engines, and it offers a private beta for early access, so it's a good option for people who want to use AI to create 3D content.