Wibblewozzer said:
Ikaruga mode is unlocked if you have Ikaruga downloaded from the Xbox Live Marketplace. I don't think there's any other way to have it unlocked.
As for weapon usage I think it's best to be versatile. On the first level I generally alternate between the primary three pretty evenly. Also, the attack that's like a radial homing attack thing is the only way to find the secret stuff hidden in levels.
I'm new to the game having played it last night for the first time so I can't really say a whole lot more. I'm curious what triggers some of the bonuses. Why do I get Special and Weapon bonuses seemingly randomly? I know about the hidden dog things but I get special bonuses occasionally without even those being around.
Weapon bonuses are dependent on certain conditions you use the weapons
Vulcan - 200 hits without missing a target, about 15 seconds hitting the target.
Homng - 300 shots without missing
Spread - 20 shots without missing
Plasma - 10 or so seconds of constant contact with both lasers.
Rear shot - 300 hits, i believe it resets if you dont hit anything for more than 3 seconds.
Homing lasers - 15 seconds on a target, dividedby the number of targets. so if you have 3 target with the laser, you would need 5 seconds on continuous fire to get the bonus.
radiant sword - 5 seconds of contact with an enemy.