In the Instant Apps for Game on the Play dev guide, I noticed they officially support a plugin for Unity as well as one for Cocos2d.

It would be interesting to try this to see how an android game can be made using that: https://cocos2d-x.org/ 

https://digitalocean.cocos2d-x.org/CocosCreator/v2.1.2/CocosCreator_v2.1.2_20190716_win.7z 

513 MB download… will skip for PA.

The quick start here:

https://docs.cocos2d-x.org/creator/manual/en/getting-started/quick-start.html 

Shows:

• It seems to come with an editor, kinda like Unity.  Asset library, etc.
• Programmed using JS, CoffeeScript, or TypeScript.
• The example uses the “old” property-dict style for creating a JS class.
• “Custom components” are JS classes with properties.
• Creator “nodes” are manipulated.
• A custom “jump action” is created by combining interpolators.
• Typical key events handling.
• “Prefabs” are used to duplicate assets.
• Object collision is programmatingly done by computing asset-to-player distance.
• Overall “score” audio and effects.

Overall it seems like a (suitable?) replacement for Unity in 2d, as long as JS is acceptable. Using TypeScript or CoffeeScript may make the JS a tad more palatable. Integration with Android remains to be seen, as well as runtime size.