>>9730337The classic series is gen 1 and 2 which are currently being rereleased. They have the most basic gameplay and are the most accessible.
The Connection series feature "Version" 1-5 with the first three being similar to the classic series but with significant improvements, feature additions, and much larger rosters (at least after version 1)
Version 4 and onward begin to add fluff that end up taking away from the core experience like raising multiple Tamas at once, or finding them a career. Some people prefer this, but imo the Connection V3 is the final model to really feel like a retro virtual pet before too many distractions are added. It's my personal favorite.
The modern series are all color devices, each with their own gimmick and more focused than having a virtual companion than an actual pet that can die and has needs to supply.
The Nanos are a line of miniature Tamagotchis all themed to popular franchises or tie-ins like Pac Man, Star Wars, etc. They are fun distractions but heavily strip down the Tamagotchi experience and difficulty to instead work better as a keychain or accessory that you really only need to check on once a day.
Hope that helps. I'm happy to answer questions about my incredibly autistic hobby.
