Away from the battlefield, the only other new feature requires a link cable and a second copy of the game to take advantage of. As you'd expect, the two different versions of the game (Blue Moon and Red Sun) contain their own exclusive subsets of Navi opponents, battle chips, and in-game events. Besides being able to battle your friends and transfer battle chips between two cartridges, this new game also lets you send tournament data back and forth--a process that allows players with one cartridge to collect rare Navi cards and unlock events that would otherwise be exclusive to the other cartridge, and vice versa.
The worst aspect of the game is the story. The previous games were set up so that Lan and Mega Man were constantly meeting new adversaries and uncovering clues that led from one boss to the next. The running back and forth and the random battles seemed relevant to the story. The events in this latest installment revolve around an asteroid that's on a collision course for Earth. But, and this is the kicker, Lan and Mega Man don't play a role in this plot point until the very end of the game. Lan ends up running errands for people and competing in tournaments for much of the game, while the adults around him work hard to put together a giant laser to fire at the doomsday rock. The bad guy isn't established until very late in the game--and even then it's just one guy! The end result is that what you do rarely ties in with the overall story, which means that there isn't much payoff for all of the random fights and searching around you're forced to endure.
Attacks can gobble up multiple grid spaces. Some chips allow you to shatter or steal enemy grid spaces.
Like so many other things in the game, the graphics and audio haven't changed much since part one came out in 2001. The character graphics used for Mega Man, the other Navis, and the viruses shown in the battle scenes look like they were ripped straight from the old Super NES Mega Man games. The backgrounds and floor tiles in the battle scenes still don't use more than a few colors, and you'll only notice animation loops when the background or the terrain, such as grass and ice, call for it. Out in the real world, the three-quarter-view environments and bigheaded characters look just like what you've seen in the majority of other GBA role-playing games--except that the environments haven't been gussied up with extraneous artistic details or animation loops. The music and sound effects, as has been the case in all three previous installments, are a blend of techno music, Mega Man-inspired themes, and serviceable pops and explosions that fit the action without going overboard.
Feature for feature, Mega Man Battle Network 4 sounds just as good as Mega Man Battle Network 3 was. Unfortunately, the flaws are tougher to ignore this time around, partially because the few, new tweaks don't make the game more exciting to play but also because the story is so far out in left field that it doesn't support what actually happens in the game.