It was easier to learn than the alternatives (UDK, any of the Java engines) and consistently added clearly useful features.
Jump to 2019, their networking solution, UNet is abandoned. Multiplayer is a perhaps a top feature developers/players want. A great open source library called Mirror picks up the slack, but Mirror wasn't made by Unity.
As other commenters have mentioned, easily compiling to iOS made it a clear winning choice for game app development.
Re:Unity Software Inc S-1
by appleflaxen on Wednesday August 26, 2020 @02:41PM
(#24285756)
Thanks for the reply!
What made the engine rise to prominence in 2010-2015, in your view?