I suspect you are correct. It looks similar to the doom-for-android. Plus they are likely leveraging and violating the use of "FreeDoom" name (
http://www.nongnu.org/freedoom &
http://savannah.nongnu.org/projects/freedoom ) which is an actual project that's been around over 3 yrs. The "FreeDoom" site makes no mention on their front page they've released an Android version. And they surely wouldn't include adverts in it. However, the FreeDoom project has a modified BSD licensed for use their code as one pleases. I'm not going to install it to look into the about screen, credits, etc. as I don't trust it at this point.