Alexa Web API Is Now Generally Available

The Web API extends Alexa 's capabilities with the power of the web to help developers create immersive, more engaging gaming experiences.

Amazon announced the general availability of Alexa Web API for Games (Web API). Alexa Web helps games developers create API visually impressive, animated, multimodal Alexa games using HTML5, Web Audio, CSS, and Javascript. It also enables you to create 3D experiences with WebGL, efficiently.
Amazon said that Alexa Web API is supported on all Echo Show devices and select Fire TVs. You can use the Alexa Presentation Language (APL) to build the visuals for all Alexa devices with screens.
Source: Amazon 
If you want to create web-based games that users can play on Alexa devices and use features that are not available in APL, you should use the Web API.
"Alexa offers accessibility like no other voice service can. Being able to expand upon the voice interface by adding a draggable chess board and dynamic visuals enhances and underscores the immersive experience I want to build for customers. With the Alexa Web API for Games, I was able to leverage modern front-end design and WebSockets to create an adaptive and rich experience that allows users to control the chess board however they choose." said Ryan Jordan, head of LC Publishing and creator of the skill Chess Maven.

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