Cross-promotions seems to be a popular way to do it.
Do more cross-promo on Patreon. I literally rolled through your entire Patreon feed and there has only been one, and it's fairly recent, with a dev that has roughly only the same level of support as you. Try to do more with more popular devs.
Do more cross-cameos in game. I know it's harder for a cameo to make sense for a game set in an undetermined future timeline, but there are no rules that says the cameos have to be related to the original game's story. Get creative. Maybe the cameo can appear as your characters watching some kind of entertainment or documentary from the distant past? Or them playing some kind of video games?
You've got a character jealously guarding what's on her laptop screen already, hint hint.