PlayCanvas vs O3DE (previously Lumberyard)

PlayCanvas has an online editor that lets you build scenes and work with other people in your team in real-time. This is all done through the web browser without having to install any additional software.

Assets and content delivery is very different on a web platform comparing to native. So PlayCanvas challenges best practices to allow developers decide how their content is delivered and in what form.

Async Assets download allows developers to load content as the app goes, instead of asking to download all assets in advance risking users to simply navigate away while staring at loading screens.
Formats for 3D models and textures support covers all the popular tools. And the workflow is as simple as dragging and dropping your files right into the Assets Panel. The cloud will do the rest of the hard work optimizing and converting your files into runtime-friendly and compressed data.

Has an advanced WebGL renderer that runs in the browser.

Lightmaps are an efficient way to deliver lighting to your scenes for a long time. But they come with the cost of large textures. PlayCanvas offers a unique solution for a web platform, it renders lightmaps when an app is loading in runtime.

This is faster than downloading MBs of textures. And it's much more convenient: simply switch your light sources to bake, and static models to be lightmapped, and the engine will do the rest.

PlayCanvas has Feed as homepage for registered users, listing Dev Logs of other developers. This allows to socialize with other developers like yourself in a twitter-like environment.
More to that, there is also an active forum, where developers help each other to solve their challenges.

Developers of PlayCanvas itself are always looking forward to chat and help the community with any problems that may arise.

PlayCanvas lets users integrate physics in their game rather easily, using the powerful Bullet Physics Engine (ammo.js). Should also be noted that the physics engine is delivered as an optional library, so by default being disabled it does not add any extra download size to your apps.

Engine is free for projects under 200MB and with no more than 2 people on a team. The free tier has no engine restrictions.

Tools are totally free too. There are no special limiting features behind any paywalls, and free users have all the features as paid users.

There are no royalties associated with publishing your apps and games - you've made them, you own them.

It is free to publish to playcanvas.com as well, just by one click in Editor.

PlayCanvas lets you build games that run in mobile, desktop browsers, and native mobile apps. PlayCanvas can even make games that can run inside mobile social media and instant messenger clients like Twitter and WhatsApp.

The engine itself weighs just under 150Kb, and it's always challenged to stay small. There is no extra weight that has to be carried with your app, just your assets and scripts in a runtime-friendly compressed form.

This allows users to engage with your content in matter of seconds, and even just under a second on a good connection.

PlayCanvas is fully open source and is under active development.

Real-time link between your launched app and the editor allows the developer to preview and play with their scene without needing to refresh the game after every change in the code to see the updated result.

As a proof of how much Amazon is committed to the project.

Advenced stereoscopic reprojection to save rendering time.

Sculpting and painting tools for terrain and instanced details.
Procedural generation of terrain.

Built-in support for roads and rivers to ease the design of rich game environments.

Full source code for Engine Editor and every tool.

Thanks to built-in terrain, time of day, ocean and volumetric fog systems. There is also a gfx pack with various environmental meshes, cloud, particles, materials and skyboxes.

Multiple entity contexts, reflection, serialization, replication, script binding, event bus (EBus) messaging, fully cascading prefabs (slices).
Every reflected property can be fully exposed in the editor with a customizable gui control and can be animated in the built in animation tools.

Online oriented plugins composed by both client, server and administration components to easily add various online capabilities without further work (es leaderboards, login, message of the day, downloadable contents).
Since version 1.7 they has been released at a steady rate.

Very advanced 3D prototyping tool with many modeling features and UV mapping support available. If you want you can build any kind of fully textured static mesh without relying on external tools.

Realistic looking lighting bounces.
It doesn't require long offline precomputation times like other static and dynamic GI solutions based on lightmaps or other similar techniques.

Other than common aws functionality it supports game specific Game Lift for autoscaling game servers.

Modular workflow and flexible cascaded propagation of changes.

To easy add and remove modular functionalities to a project and easy share them.
Modules are called Gems and can contain code and/or assets.

Tessellation and Displacement.
Various Parallax Mapping techniques(POM siluette).
Translucency and Sub surface scattering.
Detail Mapping.
Material Blending.
Emission.
Advanced uv transformation and animation.

Global environmental volumetric fog and/or hand placed custom shaped volumes with featuring full lighting and shadows.

Amazon made available a selection of triple A quality scenes filled with high quality assets.

Implements the most recent technique available (published in 2017) from Anton Kaplanyan.

You can modify shaders while testing the game.

Shader files are modular and annotated to setup the material editing gui and filter out mutually exclusive options. All shader permutation are compiled almost instantly from the asset processor and cached for later use.

You can create games that react to keywords entered in a designated Twitch channel and let streamers to invite targeted viewers into their game sessions on demand with ease.

It is still possible to use the non LTX version with few changes.

Built-in Lua editor with remote debugger to debug Lua scripts running in any device.

Optimized versions of assets can be streamed live to any device connected over the network.
This makes possible to implement asset types that hot reloads reducing drastically the time to test new content and little changes on device.

Multiple grain of control over any kind of engine setting and various kind of Lod systems. Settings can be grouped and applied in batch.

Perforce also comes with a free version for a limited number of team members.

Has skin shaders with subsurface scattering and weighted wrinkle maps, eye shaders with refraction parallax, hair with anysotropic specular reflections, etc.

A must for problematic things like hair , vegetation and scenes with complex solid transparent objects(es glass of water with ice cubes).

Special iteration of Temporal AA to battle the ghosting issue omnipresent in engines using other Temporal AA techniques.

It now works for both static models and animations and support advanced setups(es lods and physics).

Updated renderer pipeline to leverage the full spectrum of precision, luminosity and image processing features of the latest HDR tv.

Animation Spline editor supporting huge range of keyframing and tangent editing tools.

The UI uses the entity component system so it's fully modular and easily expandable. The UI is easily skinnable and supports border scaling images (scale 9). Powerful layouting system supporting multiple screen resolutions. Being based on the entity system every property can be fully animated.

It is elegantly managed in a separate entity context so it doesn't get messed up with other kind of entities and their components like in other engines, but it's fully decoupled communicating with entities in other context on specific event buses.

See here.