These folks put Spelunky (1) in Spelunky (2) so you can Spelunky (1) while you Spelunky (2)
Spelunky 1 is the best game ever made. I prefer its pacing, difficulty, and variety to its sequel. And yet if I was to recommend one of these games to a new player, I would find it difficult to advocate for the original. Spelunky 2, released eight years later (and twelve years after the original freeware version), has better player movement, better art, and a dozen small design changes that make it a smoother experience. Spelunky 1 is the better game - the best game! - but it feels old by comparison.
Enter the creators of the HDMod for Spelunky 2, which recreates the original Spelunky's world generation, enemies, characters and items within the sequel. So now I can play Spelunky 1 inside Spelunky 2 and experience the best of both.
"Spelunky 2 feels like an improvement in almost every aspect," says Super Ninja Fat (SNF), one of the mod's creators, speaking to me over email. "The engine alone made many fixes, mechanic improvements and quality of life changes over the original. However, many fans like myself miss the first game's pacing and content distribution."