haha, beating all these challenge seems harder than completing the 1999 mode... or lets say it's at least way more frustrating.
13. (Soldiers, Volley Gunners): Defeat 5 enemies with a single Devil’s Kiss blast -
no idea how i should obtain this... i even upgraded Devil's Kiss, but only managed to kill 2 enemies... and if you fool around, just to let enough enemys alive and to wait for the perfect momemt, the risk is very high to just die and fail the challenge + you have repeat 12 waves. yay! -_-
i would prefer the normal difficult, instead of the hard one.
hopefully someone makes a video for this challenge or tell me a good solution how to complete the challenge.
btw: at the moment i save my money for the gallery & upgrades, but after buying all stuff, i guess you can waste your money for extra lifes... i didn't bought one so far, but if you spent 500 dollar and die, do you fail the challenge? and can you buy more than 1 "extra life" ?