I used to just delete them, as I had no longer any use for them, but lately I've decided to keep them around for preservations sake, as I have lost many a good idea that way. About 90% of my projects never even get released, (not even a demo) but often contain interesting ideas that I like to incorporate into my current games, but that is sort of hard to do as pretty much all the information that surrounds that project is lost to time and only accessible by my memory and various clues in scattered drawings. journals, and text documents that can help trigger my memory. Here are all of my unreleased games, for anyone who's curious.
Chronicles of Light: My first RPG Maker game which was made in VX Ace in 2014 or so. It was very poorly made, but was fully completed. I incorporated many ideas found in it into my latest project, Meteo Chronicles. The files have been lost to time.
Elvengard: My second RPG Maker game also made in VX Ace, created in mid to late 2014. I never even got past the prologue, only making the opening cutscene and a single battle. The files have been lost to time.
Zero Gear Fighters Gaiden: Blood of Darkness: A short side-game connected to Zero Gear Fighters, my first released RPG Maker game, featuring the "tragic" backstory of one of the main characters from that game. I was never completed because MV could not properly run on my old Windows 7 PC from 2009. The files have been lost to time.
Strange Dreams: An adventure game made in VX Ace in 2016. It was never completed, though I did make decent progress on it. It was cancelled mainly due to me not being ready to handle the material yet, and also because I prioritized other projects around the same time. The files have been lost to time.
Stardust Saga: An RPG made in MV made around 2017 or so. I never got far in it, mainly because MV still couldn't run on my computer. I still have the files to this day.
Draco Anima Origins: An RPG made in VX Ace that began development immediately after Stardust Saga was canned, now made in VX Ace. This is around the time where I straight-up swore off MV "forever" (not really) and decided to work solely with VX Ace going forward. I actually got pretty far in development, getting up to the first dungeon before quitting because making an FMVs was too hard for me. (yes, it had FMVs, made in Windows Moviemaker of all things.) I still have the files to this day.
Legend of Dragoon 2: Rising Suns: A Legend of Dragoon fan-sequel made by someone who never played Legend of Dragon. It never got far in development because I couldn't comprehend LoD's battle system from the Wikipedia article and couldn't find any good gameplay on YouTube that wasn't a 250 part let's play.
After the failure of LoD I got a new PC and began work on Generic RPG Quest III, which turned out to be far more ambitious then I imagined and had to be canceled. After that I made Crypt Challenge DX within 2 weeks and released it, then going on to make my current project, Meteo Chronicles, which I am nearly finished with.
Other me: Get rid of it to get free space for the disk and Other me: Keep it there. There lots of idea I want to work on and it's tough choice about my old project that I can't decide what to do with them, all of them still lying on the disk (I am looking at MV project since I can't decide to do mv or mz)
I used to delete everything, and then I started writing for a while and learned a pretty neat trick I call the "sweetening file". Basically just chop up my ideas or my favorite pieces and compile them into a folder so that over time I can improve on them and eventually use an old idea for a new project. This way the effort isn't wasted and you have a lot of back up ideas just waiting to be used and refined.
I threat old and abandoned projects like a library. Parts of an abandoned project might become useful later. Also when working on a project you will have to overcome many hurdles. Sometimes you can run into problems you have solved before but can't remember how you fixed it. Whenever that's happening I look through my old projects to see how I did it then and if I can apply the same solution know.
If I can't do that, I'll at least keep them around as eventing repositories like that one person said in case I need to remember how I did that one thing that one time.
The stuff I had truly abandoned was far and away so old that I've switched between computers and they were generally not good enough to even use as beta fodder... though I do wish I still had them if only to make fun of them.
When I scrap something I typically will take some of the old ideas and use them for something else down the road, whether its a short story or game it varies, but the scrapped ideas usually have potential, maybe I was just in a different head space to make it work effectively in the old project, but maybe NOW it can work in this new project!
I tend to use my other projects as testing grounds! I only have 3 projects at the moment, and my very first project followed a few tutorials. I still keep it and use it to test things I want to do in my other game. Though in general, I keep things even if I don't finish them and have a feeling I won't work on them.
ohh man im ending oneshot now (im doing the last stepping puzzle rn) and the music is so...sad...like...ive been thinking recently about how fast moments pass and...my anxious thoughts combined with that music and nostalgia...like...im comfortably sad...and want to cry internally