Finally decided to do a solo marathon run on this map completing the EE, to make it short I must admit it is too slow for my liking, I got to 63 but after 60 I was running low on ammo constantly and it was effecting time dramatically, it took about 8-10hrs for the whole gameplay while I was shooting for 70 initially, I simply gave up as it was taking too long. I used ice staff strategy by G2 when I had full ammo, this only worked for 1 or 2 rounds before more ammo was needed and caused a failure to the plan.
Now here is the fun part, earlier when the map just came out I did a speed run to 50 which took just under 4hrs solo, and also was done with 2 and 3players under 5hr mark. Yip forget about EE, forget about staffs, forget about other little bonus crap you can get on this map and concentrate on speed play!
The start is simple… get to Crazy Place asap preferably at round 7, one player stays there to train yet kill them as soon as they can obviously… while other players camp outside, note that if you got 100z to clear the round, 90 of them will spawn in the crazy place while only 10 up top. Eventually you will run in to ammo issues and it will happen somewhere between 30-40, just get the maxi drone and release in the crazy place, no ammo needed to finish the round and he kills them as soon as they spawn, the drawback to this strategy is it will not count kills but will finish round 40 in 5minits without using any ammo, so when drone brakes have other players ready to pick up a fresh one. This is by far the fastest strategy I have come across on this map, enjoy.