Some Improvements and Additions in this installment of PSO features an entirely new episode that includes 5 new regions to explore: Temple, Spaceship, Central Control Area (consisting of the Control Area, Jungle, Seaside and Mountain), Seabed, and Control Tower (Control Tower is available in Online mode and in the offline Episode II Plus version quests). This installment also adds 3 new character class/race combinations, many new items, many new creatures, and some added cheat protection (however, cheats and glitches were still found and exploited, rarely being addressed by Sonic Team). You can also play on-line with the Gamecube if you have a broadband adapter or modem adapter. Data between the previous Gamecube version and the Plus version is completely (and instantly) transferable. One note, the game was prone to locking up the system and corrupting the player's memory card, which would then need to be reformatted, causing a loss of all data on the card.
This is the only other game on the GameCube to make use of the GameCube's broadband modem adapter, the other being "Homeland" which only saw release in Japan.