Amazing! How long it took you to do The Mummy Demastered 17? Or graphics to Tower 57 (by the way I am playing it now Could you to step by step tutorial on some complex design like The Mummy Demastered? (with tips)
Most of the Mummy scenes took at least 3 full days of work. Since it's a game and assets sometimes get reused between scenes and sometimes you have some iterations, time can vary heavily throughout the development.
Mummy was in prodcution for roughly 6 months, so overall it was done on a neck-breaking pace.
I worked on Tower 57 from December 2013 to November 2017 with quite a significant amount of breaks inbetween, aside from middle to 2015 to most of 2016 where I spent fulltime hours on it.
A step by step tutorial for something as complex as a complete game scene would be simply to long.
Since all of that is game art and not just pretty illustrations, there are so many considerations to make regarding the gameplay, the tileset, reusability of elements etc. and it's so highly specific for each project, that talking about that in a tutorial would be too specific.