There are a LOT of different game engines out there which allow the hobbyist or independent developer and small studios to develop small games rapidly. One of them I've tinkered with on and off for years is Game Maker.
Since Game Maker Studio 2 just came out recently, version 1.4 - and addons to allow game files to be exported to Android phones, iOS, and web (HTML5) - is currently on sale for $15 or less (depending on whether you just want the core program for Windows/Linux, or more).
http://www.humblebundle.com is a games-on-sale site where you can pick up the whole studio collection for $15 for the next few days. The programs and games included normally cost around $1,600! I just bought the studio collection myself, testing everything now.