 The team found developing an RTS for the Nintendo DS to be difficult, and had to start development over at one point.Although prior to the "World of Mana" project Ishii has said that the games in the series are only thematically connected, "Heroes" is explicitly set as a prequel to "Trials of Mana" (1995), depicting battles between the nations present in that game.It is set one generation prior to "Trials of Mana", with some characters noted as the parents of characters in the other game.