That's an angle I completely approve of, of course
What I found appealing with Unity, was the cross-platform aspect, ironically. But I came over an open source alternative called
Godot (MIT License, compiles to Android and iOS as well as desktops and a few other devices). It seems quite decent to my needs, so I've decided to try that for the moment. Java would probably have been the "better" option, rationally speaking, and I'd never even actually considered using a game engine as opposed to mucking about with compilers et al in my beloved terminal, but I thought, meh why not try something new?
I'm sure it will feel limiting at times, but on the bright side it's quite quick to pick up and play with. After just a few evenings of bungling around with the (rather incomplete) documentation, I've learned some basics and put together an almost finished Pooyan clone
The engine uses a scripting language similar to Python, but stuff like the main loop, redrawing the screen etc. is kept out of sight. To a perpetual noob like me, it might be a good companion, but there's of course a special pleasure (and, probably, consistency of vision in the ensuing game/program) to be had from writing stuff like engine and interface yourself.
Speaking of which, I need to get back and give Land of Strangers some loving soon. I was just about to add some intelligence and personality to the NPCs. Just having a few quite hectic months, ahem.
As always,
Minotauros
tl;dr: Godot seems like a good alternative for anyone looking for a game engine.