Will I be able to change back to the default OS if needed?
I couldn't find any answers to this question and I'm sorry if I'm asking a question already answered
Thanks

You cannot install Doors on a TI 84+ CE.

Just install Cesium and everything works the way you want.

I addition to this, shells like Doors, Cesium, etc. are not an OS. They run with the default OS, they do not replace it. If at any point they freeze, performing a RAM reset will get back to the regular OS.

Doors CS is unfortunately not available for the TI-84+CE.

I would recommend installing and using Cesium, which will enable you to run ASM and C programs/games.

Cesium can be found here: https://github.com/mateoconlechuga/cesium/releases
Depending on your calculator version you may need to install it via arTIfiCE: https://yvantt.github.io/arTIfiCE/

The good thing as TLM mentioned is that this is not an 'OS' so to speak, rather a shell that you run from within your calculators OS that provides extra functionality. When you exit the program you're back to the regular calc OS.

or you could try Vysion which is still being developed. https://www.cemetech.net/downloads/files/2095/x2227

Yep, that's another good option that's probably the closest you can get to Doors CE (well, once I actually finish it anyway). CEaShell is nice as well, with a clean interface and a lot of neat features.

Also, thanks for the promotion!