Greetings,
I would like to ask the following:
Soon I start shipping my games to Google Play nd I do not know what to expect.
My weapons of choices were Blender, GIMP, some CC0 textures and Unreal Engine. Do I have to prove I only used these? If so, how do i do it?
Or if I don’t have to, will Google just reverse engineer my games to find out themselves?
Thanks in advance for the help.
Google does not care and probably won’t check a thing regarding assets or used tools. You don’t have to prove anything beforehand and only by request. It’s a good idea to keep some sort of spread sheet of external assets used so you can quickly provide receipts or links when someone reputable ask for verification or etc. For in-house or self made assets you can just show a screenshot of the assets in their respectful editors.
In general the one who’s asking these things has to have some reason to ask. Like possibly asset authors checking if you bought their assets or someone thinking some art asset is a ripped off or derivative work. It should be very rare for anyone to ask anything if the project is full of mostly self made content.
Dont mix it up … Those who claim that you’ve stolen something must prove that you did, not the other way around 
Just check the resources you’ve used and read their liceneses.
Being too honest(from the start )is a bad thing.The only time you can get ¨audited¨ by a company is if they suspect you are using their soft illegaly(pirate),or the tax gyus can try and ask you and only if you make a insane ammount of cash.Either way the chances are 0.01% someone will want to research you.On the other hand,when you start making money the first thing you have to do is buy the software if you dont have it just in case.
Another thing is stollen 3d models.
Thank you for your advices.
I really only used the software I mentioned, part of the reason is that they are free, the other part is that really Blender and GIMP are state of the art software. I can’t draw, but can model, thus it is easy for me to use Blender to pre-render my sprites to be production-ready. The games I made are 2D only, using my own design of course. I used online images only as inspiration but 100% of the time I created my own assets.
The reason why I asked is that this will be the first time I upload to Google Play and I don’t want some exactors sent by papa Google knocking on my door.