Greetings Bounty Hunters!
I'm just curious on how do you call a failed project (project who run some features but didn't continue)
I maybe wrong but I'm considering them as "Abandoned Projects".
As the term says, abandoned meaning they tried it but failed so they abandoned it

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and a project who depreciated within time (projects who has lost its value due to its low demand and market value)
This I don't know. There are many altcoins who suffered this kind of scenario. I've seen most of my altcoins that I got from bounty campaigns years ago depreciated its price because of lack of support from either community or the team itself. I feel terribly sorry for those projects though that has a good intention and will do everything just to make the project successful but in the end, failed because of lack of support.
Another thing is how can you tell if it has a potential or doesn't have any?
Right now, it is hard to pick which has potential or not knowing that the project that is very beneficial to the people can become a scam in the end. I don't if there are some people here who has basis but for me, I don't have since I'm not investing into new projects. I focus on the old and top coins.