Gungrave G.O.R.E

Way easier than it seems at first. On the 3rd level you'll have some big areas with lots of guys, use your Demolition Shot in the middle of a big group for lots of Art Score, there is a point where you'll need to evade spinning rotating spikes, just after this puts you in a huge group smash a Demo shot for around 800 just there.

I was over 2.5k by the 50% mark of this level. Ever time you can use Demo shot on a big crowd, use it and build it again, using Fury and Executions also helps.