As their name suggests, forever (or evergreen) games are games that don’t have a finale or culmination, as in “The End”. These games have a very high replayability factor (meaning we enjoy playing them over and over again).
Forever games are also timeless. We can pick up these games anytime , be it the day they were released, or a few years later, and play them for months or years. We can even stop playing for a while, pick them up again years later, and they’d still be fun and relevant.
Really love games like Enter the Gungeon and Brotato. Just stupid casual fun with (for me) quite a high skill ceiling. Terraria also kinda fits that bill I think
And yeah, I know EtG and Terraria technically have endings, but I doubt I’m ever going to reach it, so for me they’re forever games :p