Very repetitive, yet it may provide some (one-use) challenge to get nice score and wave. I personally got 16046 and wave 20.
What to do if you want to get as high as possible:
1) Primary tactic is to stand as close to enemy wave as possible, spam grenades by CD and use your rifle everytime else. Use bursts of shotgun, then use single fire until rifle recharges.
2) Upgrade main weapon, aka your rifle, abobe anything else. It is your main weapon afrer all - grenade will keep its 5 second CD after all upgrades, so it can't be relied on alone.
3) Give some upgrades to grenade, too, but it should stay 2-3 levels below your rifle - since upgrade only raise damage, this level will be enough for one-shotting everything but goliath and argath, which are slow.
4) Vulcan is almost useless. Only use is, when you used all rifle energy, to use grenade, quickly jump into the ship and use all vulcan power - then leave and immediatly use grenade and rifle, this will give slight DPS bonus (vulcan is still more powerful then single shot rifle shots). You may give it few after you upgraded your rifle to level 6-8, so it retains that use.
5) Autovulcan have two uses: either when you are at map left or centre, shoting foes, let some weak/wounded foe slip through - only to be murdered by autovulcan (usually it is small flying insects), or when you were pushed to your ship, it helps your DPS alons with vulcan quick-use. Remember that both vulcans can onlt shoot forward!
6) When goliaths begin to appear, you may want to grind them for some time - wound but don't kill them until they are close and extract valuable energy from pawns they generate. Just don't do it too long, or they will slip through defences and damage the ship.
7) Protect your ship - even if vulcans are weak, they improve your DPS even if so slightly. And withour DPS high enough to take down forward part of horde, you will be as good as dead
As you can see, strategy is quite simple. When you die at wave 20+, you may write a comment with your wave and score, give 2 to the game and forget it. Or move to the Red Code 2, hoping that it will be better