When comparing Adventure Game Studio vs GDevApp, the Slant community recommends Adventure Game Studio for most people. In the question“What are the best 2D game engines?” Adventure Game Studio is ranked 23rd while GDevApp is ranked 83rd. The most important reason people chose Adventure Game Studio is:
Good for newbie game creators. Can be used for prototyping: on several occasions was used to make a demo/experimental version before creating a final commercial product on different engine.
Specs
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Pros
Pro Easy to learn tool
Good for newbie game creators. Can be used for prototyping: on several occasions was used to make a demo/experimental version before creating a final commercial product on different engine.
Pro Completely free and open source
AGS is licensed under Artistic License 2.0 and is completely free for use for creating both freeware and commercial games.
Pro Relatively well documented
Besides the manual there are multiple text and video tutorials and code samples written by community.
Pro Used for a number of high-profile commercial releases
Adventure Game Studio has been used to develop games such as "Resonance", "Blackwell" series, "Gemini Rue", "Primordia".
Pro Lots of assets available
An extensive library of game templates and script modules accumulated over years. You can construct a simple game in hours (if you know what you are doing).
Pro Friendly community
An old, big and active community which would support newcomers not only in learning basics of the engine, but can help with every aspect of game making (including art, voice acting, moral support, etc).
Pro Quickly add behaviors to objects
Prebuilt behaviors can be added to objects. This is a very efficient way to add a physics engine or make a platformer game.
Lots of behaviors are included, from the most advanced (Physics, platformer, top-down movement) to really simple ones (like the behavior to destroy objects when outside the screen or the one to drag objects with mouse or touch).
Pro Powerful events system to create games without programming
No need for coding using this system which is clear and powerful: events are composed of conditions and actions.
Actions are launched when conditions are fulfilled. This is a very beginner-friendly way of making games and is still efficient for advanced usage, contrary to most other "block"/"drag'n'drop" systems.
Pro Intuitive interface
Pro Based on GDevelop
The entire webapp is based on GDevelop, an open source native game development software available for Windows & Linux, so it benefits from its advanced development.

Pro Can download an archive of the game source
Even though the tool depends on having a server up and running, you can download a copy of your game to run locally, or host somewhere else.
Pro Great UI
Sleek and user-friendly UI.
Pro Can export your game as HTML5 and for Android
Games can be packaged for Android without relying on any third party tool. You can also export your game and download it to host it on your server or let it be hosted on GDevApp.com.
Pro Shallow learning curve
Cons
Con Natively supports only 2D
2D only native support, 3D could be supported with plugins though.
Con Uses dated tech
Engine is based on the old technologies, which impose number of limitations and may cause problems on latest systems (level of annoyance varies depending on your priorities).
Con Graphics renderer is a bit dated
Graphics renderer is not well optimized for high-resolution games and complex effects.
Con No visual editor for scripts
You have to actually write all scripts yourself.
Con Development is slow
Further development of the engine is currently slow, done by only few people in their free time.
Con AGS Script isn't as full-featured as other scripting languages
Its own scripting language has lower syntax capabilities compared to modern script languages.
Con Assets cover almost exclusively adventure/quest genre
The features, script functions and game templates are very biased towards adventure/quest genre. The non-adventure games were made in AGS (2D shooters, platformers, turn-based strategies), but their development usually requires to write everything from scratch.
Con Workflow is closely coupled with the editor
Workflow is very tied to the editor and custom file formats, which can cause problems for bigger, more professional projects (interfering with source control, parallel development, automated builds, etc)

Con Depends on a hosting service
If the website goes down or closes down, you'll no longer be able to develop your games using this system (but you can download a backup of your game from time to time and open it with GDevelop).
Con Cannot deploy native games
For now, games developed with GDevApp can only be deployed for the Web. Android deployment is in the works, but even then, they won't be native since they are built with web technologies.
