Hello.

I got stuck at 3rd mission (desert) in the last level. Whatever I try, I cannot manage to succeed with that limited repertoire of weapons.

First I shoot the lower worm with the gun than the higher one.
But then I cannot pass the automatic guns without getting killed.

Please give me some hints.

Sorry for bad english.

You have an unlimited amount of girders in this level. Place them above the automatic guns so they won't shoot at you.

Nutze die Stahlträger um dich vor den automatic guns zu schützen. Du hast unendlich viele davon - ich habe 3 Stück benutzt, glaube ich.
Ich schieße übrigens zuerst auf den höheren Wurm, und dann auf den niedrigeren. Andersrum wurde ich ein paar mal vom höheren gekilled.

Yes, this was the solution I also found out in the weekend. Although thanks for your tip.