the unity engine gets given a bad rap, so i thought maybe i'll tell some stuff about about how the unity engine itself works, and why developers like it.
WHY IT'S POPULAR
it's popular because it's easy.
in one area of the UI you have an asset folder. you can drag and drop stuff into this folder, or generate some as in-engine components, or you can even import stock unity bases for a surprisingly large range of game genres.
for instance, there's a stock racecar you can import into any unity file. if you had a city built up, you could just instantly have a racing game. there's a stock fighter jet. a stock 360-degree camera. a stock first person character. etc.
objects exist in separate game scenes, which load between each other at code command for various reasons, some of which are functional.
objects have a few properties, but can have components and assets dragged and dropped onto them from the asset folder.
if you can build the files needed for it, unity can probably do it with simple drag and drop modules.
one component class is scripts which do the complex shit. these too, are drag and drop items. public code variables are able to be filled from within the unity engine itself, after putting that script on any compatible object.
all of this is very, very, easy to use once you know how it works.
WHAT UNITY IS GOOD AT COMPARED TO OTHER ENGINES
unreal engine is probably the largest competitor to unity, and i've looked into arguments for both.
what unreal is good at is fidelity, and it can look visually better. it works within a game world that is preset within its bounds. IE at the edge, everything stops. this means having to precisely measure your work for spatial size. it's good for indoor, contained, and controlled environments and genres.
unity can look a bit worse (or better, depends), but there are ways around that. as i've said, it's pretty easy. there's an important difference here though. unity operates within free bounds for the game world. IE just build what you want, the world goes on forever. for genres that can involve large amounts of map space, unity is very good in that regard.