Jack in and unleash the power of the soul in Mega Man Battle Network 4 Red Sun for the GameBoy Advance. Lan and MegaMan.EXE return for a new adventure centered around the N1 Grand Prix tournament. This installment introduces the "Double Soul" system (Soul Unison), allowing MegaMan to sacrifice a chip to transform and adopt the abilities of defeated enemy Navis, such as GutsMan or FireMan. The game features a "Dark Chip" mechanic, offering immense power at the cost of permanent HP loss and moral consequences. With multiple tournament scenarios requiring multiple playthroughs to see everything, this entry adds significant replay value to the grid-based action RPG series.