A work in progress engine for 10 years that has recently made huge strides in the field of features and usability.
Ranked in these QuestionsQuestion Ranking
Pro Light weight
An amazing minimal download size at around 100mb.
Pro Easy to use
Engine 001 allows you to get to making games quicker since you aren't putting allot of time into figuring out complicated interfaces.
Pro Visual scripting
By using pre-build behaviors\actions and more you can 'program' your game by simply 'linking' they in the editor.
Con Windows only
The editor is Windows only, no OSX or Linux versions are planned.
Con 3D features may not be enough for some users
The 3D capabilities of the engine are a bit limited (for today standards), and some of the times you'll need to work around to create something.
Con Not for beginners
Even those few tutorials don't teach you the very basics, and first you must learn the basics somewhere else (the submitted pros are by professional guys).
Con No successful/ good games
Just ask them about games made with this engine and you will see that even if you find some good games, those are mostly simple/small ones.
Con Poor performance
If you want to use more than a few actors/light/events, or you're trying to get a pretty look, you will get a significant drop in frame rates. This is especially true if you want to implement a moving light (something like a flashlight).
Con New tricks for getting more money
As it doesn't have enough tutorials, and they don't wanna make more, so they just add some new services about one on one help which that cost 40$ for an hour.
Con They don't fix the bugs for you quickly
If you encounter a bug or problem and report that as bug report, it will take about 1 week to get any answer, and if they solve that, the fixed version will just come up with next update for engine which that isn't be soon and no specific time, so maybe you have to wait for one month.
Con Some workflows can be confusing
Sometimes you have to do a time-consuming workaround to just do a simple function.
Con HTML5 export is poor
There are significant drops in frame rate; some bugs that can even ruin your game (also, looks like just run on firefox).
Con No IAP or Ads support
Are you a mobile developer? If so it's good to know that it has export for ios/Android but no support for IAP or Ads.