Missable content

This page lists items and content in the series which can be permanently missed, or become more difficult to obtain, if not obtained by a certain point in the game.

Mega Man Battle Network 4

Viruses

For most viruses, lower versions can be encountered even on the highest difficulty (Continue 3+). However, there are a few viruses that only appear on a specific difficulty. As a result, this may lock you out of obtaining certain chip codes, which can otherwise only be obtained (very rarely) from the Chip Trader.

Difficulty	Virus	Missable chip codes	Alternatives
Game 1 only	GaiaEX	BigHamr1 R	Can be obtained from Chip Trader.
	CirKill	-	All codes can be obtained from CirKillEX.
	BomBoy	-	All codes can be obtained from BomBoyEX.
	WindBox	-	All codes can be obtained from WindBox2 and WindBox3.
	VacuumFan	-	All codes can be obtained from VacuumFan2 and VacuumFan3.
Game 2 only	Mettaur2EX	Guard2 *	Can technically be obtained from Chip Trader, but only through a redraw, so the odds are nigh impossible.
	SillyEX	-	All codes can be obtained from Silly.
	Gaia+EX	BigHamr2 W	Can be obtained from Chip Trader.
	KilburEX	SidBmbo2 H	Can be obtained from Chip Trader.
	Webby	WhitWeb2 E WhitWeb2 Y	Can be obtained from Chip Trader. Also, WhitWeb2 * can be obtained from WebbyEX.
	CirCrush	-	All codes can be obtained from CirCrushEX.
	MilkoEX	-	All codes can be obtained from Milko.
	WindBox2	-	All codes can be obtained from WindBox3.
	VacuumFan2	-	All codes can be obtained from VacuumFan3.