Soda Dungeon was created with OpenFL (http://www.openfl.org/) which is more of a framework than an engine. I'm looking at switching to Unity for future projects though. I'm not sure if I can fully recommend OpenFL to a newcomer or not :/
I use a proximity sensor service on my older S7 (it doesn't work on my S10 but I'm sure there's something similar).
It turns off the screen (and totally off, not just dimmed or low fps, so it disables touch input which helps the battery as well) whenever the proximity sensor is active.
And the sensor is always on anyways so it's not using any extra battery there. So cover the phone's sensor with something or flip it over and off the screen goes.
https://play.google.com/store/apps/details?id=ss.proximityservice
It's on the list but bugfixes and balance changes are the priority right now, so it'll be a while.
I love the below service but it only works on my older phone. I'm sure there's something like it you could use for a newer phone.
https://play.google.com/store/apps/details?id=ss.proximityservice
Basically it turns off the screen when covered or flipped over, but the apps continue to run. B.c. it turns off touch input and screen buttons it saves a lot more power than just turning off the backlight.
I use a proximity sensor service on my older S7 (it doesn't work on my S10 but I'm sure there's something similar). It turns off the screen (and totally off, not just dimmed or low fps, so it disables touch input which helps the battery as well) whenever the proximity sensor is active. And the sensor is always on anyways so it's not using any extra battery there. So cover the phone's sensor with something or flip it over and off the screen goes.
https://play.google.com/store/apps/details?id=ss.proximityservice
Also available for Android Early Access right now:
https://play.google.com/store/apps/details?id=com.armorgames.sodadungeon2
If I search Cookie Collector 2 in the Store I just find the Cookie Clicker 2 and the Cookie Clicker Collector from PixelCUBE Studios.