Spelunky 2 was announced in 2017 and showcased its first gameplay trailer 2018, which is also when it revealed a release target for 2019. Unfortunately, it does not look like it will happen.
Hi, Spelunky fans! Unfortunately, I do not think we will release Spelunky 2 this year. Development is still going well and we are not far from the goal, but the game's density and detail require more time. Thanks for your patience. pic.twitter.com/BJvsHUWAY0??19459006achteAugust 14, 2019
"Also apologies for the lack of updates! It can be tough balancing communication and dev-time (and not be ashamed). When things are quiet, we will only to work away. There will be more updates, but for the moment we are focusing on development, "Yu, the designer of the original Spelunky, said in follow-up tweets.
Yu suggested that the extra time required could be the result of a response to the trailer. "Although I still love the overall style, we've added more detail, as well as increasing the contrast to make existing details pop (some were quite subtle and compression wasn't friendly to them)," he said.
"As soon as we have a release date for # Spelunky2, we should make sure everyone knows! We can't wait to show you more, although of course it's the best way for you to experience it yourself at launch. Everyone crazy stuff we add makes me buzz with excitement. 🙂 "
So it's still technically possible that Spelunky 2 will be out this year, to the extent that Yu didn't come right out and say it won't be , but it certainly does not sound like it will happen. I think we can safely mark this by 2020.