dang, boss walked in and i didn't get a chance to pause it, The below strat worked fine though through 42, and probably will work for a good 4-5 more levels. Good luck guys! i'm out of this page for a long while
(Post 1/3) Finally, after about 2 weeks of trying.... I went back and did a combination of these two strats posted by Calyad and modified by TBH_Productions.
just follow the steps, don't worry about the days.
step 1. buy 1 gunman
step 2. buy a combat shotgun (you will use this the rest of the game, for the tanker truck at the end)
step 3. buy a quake machine, put it in the top spot, don't upgrade you will be selling it.
(post 2/3) step 4. buy 1 repairman
step 5. buy a missile launcher and put it in the middle slot
step 6. upgrade number of missiles to max
step 7. buy a laser tower
step 8. upgrade rate of fire to max on laser tower and missile launcher
step 9. sell quake tower and buy laser tower
step 10. max out rate of fire on new laser tower
step 10. max out damage on laser towers, do not upgrade damage on missile launcher you will be selling it
step 11. start buying gunmen and repairmen, you will want a ratio of 2 gunmen per level (if you are level 25, you'll want 50 gunmen) Do this for the rest of the game, even beyond level 41.
step 12. when you have at least 45 gunmen, sell your missile tower and buy your last laser tower
step 13. upgrade all towers while throwing in engineers.
(Post 3/3) step 14. buy the orbital laser, upgrading #of shots first. (you will use the orbital laser for the huge guys and the tanks, 1 shot for a tank, 2 shots for a huge mech)
step 15. upgrade reload rate on laser, then range. All the while mixing in engineers as always.
step 16. buy engineers the rest of the way.
this worked for me past level 40, i'm still actually playing, but took a break to write this for the benefit of others who may be struggling like i did.