I have first attempt at insane, ending with alpha06 start - stoped at guarding entrance to my half, in order to try different walkthrough. There are some tricks to make it effectively.
- First scav groups (infantry only) are easy to dispatch with just 4 tanks with to now damage - using 1 as bait, hiding in side terrain so, that scavs can see it but can't shoot without getting utterly close, with other 3 machines shooting and rolling over them without any resistance. Could be harder to exploit if AI could handle events when target becomes unreachable for weapon.
- First objective here is to get repair turret. All 4 tanks go straight to base with last derick, sneak behind (posible to not even get red units health), knock it out and retreat in reverse sneaking route to not have loses. Barell is used to get lab ready as soon as artifact is grabed, yet remaining energy is used to get 5th tank at base, shooting attackers through buildings by being manually kept in move; may be their holdposition could have effect of non-interrupted patrol, while firing everything in range. Also that base could get light fix for vulnerability at the back by adding at least 1 tower behind, though it's already really hard without obtaining repair turret first.
- One approach, most useful at insane enemy production speed - I keep as much as possible enemy factories working, keeping as final structures instead of towers to both use remaining time for oil and get reach source of experience (managed to get nearly 9 units at '|>>>' level with total 13 units at the end of alpha04 (others were '>>>' with 2 '|>>' or so.
At alpha02 first objective was to get generator module, so I rushed straight to it just after securing exit (but ignoring base right at exit), with truck and second group guarding entrance to secured zone instead of towers for experience too. I with could keep its factory intact if only knew, how to place few units behind 4th derick to shoot produced units, but not factory. Kept two other factories however, with attack group taking place at entrance to base with twin mg.
- Power module is researched and added as soon as possible - mission doesn't end while enemy factories work. Keeping upgraded generator before finish, than replacing with regular one, which is enough to produce many times more power than cost of generator, using additional 6+ minutes (also time to research and upgrade).
Others is not tricks, just more attempts to keep factories.
Factory at alpha03 base is kept until just enough time left to research HMG (even enough to make a run at top).
At alpha04 hidden factory at entrance to lab may be kept for experience.
Perhaps will try first naive way at alpha05, moving right at NP direction, provoking all to attack, to get as much as ossible experience thanks to enemy LZ at Insane. =)
(of course, I'm not so insane yet to do it at speed higher than 0.33).