Custom mode is unlocked after beating Nexomon: Extinction for the first time, introducing various options for both new and old save files.
Some of these options allow for heavy randomisation, including randomised starter Nexomon and trainer encounters. Randomisers are something used fairly frequently in the Pokémon community when players are looking for something fresh, so it’s great to see them added here.
Other options also include what are essentially Nuzlocke rules (can only capture the first Nexomon you encounter per area and fainted Nexomon can’t be restored) and the ability to transfer items between save files.
Custom mode is also coming to the Switch and PS4 versions of Nexomon: Extinction, though VEWO Interactive mention that the update “will take a while for it to be approved in every platform”.