Pokémon Ruby, Sapphire, and Emerald (2002, Game Boy Advance)

The third generation of Pokémon games—Ruby, Sapphire, and 2004’s Emerald—aren’t exactly held in high esteem by most Pokémon fans. Here’s the case for why they were terrific:

Double battles were totally game-changing. Rather than one Pokémon on each side, in some cases, each trainer could now have two, leading to some seriously complicated strategies (at least in versus battles). For instance, Earthquake, a high-damage ground-type move, would strike all three other Pokémon on the battlefield. Was it worth hurting one of your Pokémon to also hit both of your opponents? For the first time in the series, trainers had to formulate new strategies outside of mere type-matching.

The introduction of natures—unalterable aspects for each Pokémon that dictate stats—made EV training more accessible. You could look these natures up on niche guide sites, like Serebii, and get a better sense of how that Pokémon’s stats would progress. Casual players could ignore this stuff and get by just fine, but series diehards received another complex layer to sink their teeth into.

Pokémon abilities added another wrinkle to the combat by bestowing Pokémon with permanent benefits that weren’t ever game-breaking.

You could dive underwater.

Secret bases.