Monster Rancher 1 & 2 DX is a Remaster of a Playstation monster raising simulator with the ability to Fuse parents to make new babies with inherited attacks, traits, or stats of the parents. (cross breeding but the parents are consumed in the process). Like a fantasy version of Tecmo's horse racing simulator (Gallop Racer), Monster Rancher will have you budgeting your Money and your creature's lifespan to provide a balanced feeding and drill schedule to raise it's stats, learn new attacks, and fight your way to Master rank. Along the way you'll have story opportunities to discover hidden/locked monsters and raise them as well.
The original gimmick in 1999 was being able to visit the "Shrine" in game, and be prompted to replace the game disc with Music CDs or another game. When prompted again you would reinsert your game and a monster would be generated. The downside of this was it ended up leaving a lot of people excluding from a large portion of the game's available monsters to raise.
DX replaces this gimmick with a built in Song List to generate every monster, giving all players complete access to the game's entire library of monsters, along with many new variants (same given breed but with different attributes) not present or possible in the original game.
There's a Discord community for this niche game, along with the last remaining English fan-run resource/guide site LegendCup.com entirely dedicated to Monster Rancher since the 90s.
Members of the Monster Rancher community use the game's save upload system to run AI v AI tournaments across many different formats and stat caps to include players of all skill levels. The game is cross-region, and cross-platform compatible for these types of tournaments so DX allows you to play on your platform of choice.
Hope to see you on the Ranch!