i just put this here so i can compile step by step to get doom and wolfenstein on my ti 84 plus ce python edition. i hope this works but idk. ATTENTION this will only work if you have already jailbroken your ti 84 using artifice i may write how to do so eventually but i am not sure. you wont need artifice if your calc is earlier than 5.5 (you can check by clicking 2nd then + then enter and it will tell you.) it isnt to difficult and i may add the steps soon.
1st download wolfenstein Here and doom Here.
2nd now that you have these download ion here Here.
3rd add these to your calc using ti connect ce. (wolfenstein and doom should work i dont know about ion i havent done it yet. if ion doesnt work my last hope that isnt downgrading is using this huge ass file known as doors cs 7.4 found Here)
4th if that works use artifice (through cabrijr) and open up ion(or doors cs 7.4) and you should be good to play (you may have to install ion/doors cs.)
you wont need this if the above steps have worked but this is a theoretical way to downgrade first go get cermastr 2.0 from Here then transfer it to your calc then use artifice to open it up. go to the 37th file and it will say something similar to 00 08 05.(thats what mine says). click the left arrow once and the first number should turn red(you can do it several times). use the up and down arrows to make sure it says 00 00 05. one messed up number and it could frick up ur calc. click enter when ur done. then install ur os i reccommend 5.3 make sure its for ur calc the wrong one will not work. there will NOT be a 5.3 python just use the regular. then add it to ur calc. then it should stay installing if it freezes hit 2nd+enter and click the little button on the side of the calc and try again.
NEW NOTE i found a way to play wolfenstein without mirageos or downgrading cuz mirageos doesnt work on ti 84 + let alone python. use ti boy CE and use the file that says WLF3D.84 on the files on this rep.