The secret to passing all levels - machine guns that unlocked for 15 weapons factories. And seeing that they are preemptively destroying the ground enemy, we need to constantly think about aviation and build anti-aircraft guns. And in the process build a lot (about 30) money buildings.. The game is incredibly difficult if you don't stick to this one strategy, which is of course a big L. Otherwise, nice comrade!

Glory to the USSR

So it's NOT real time strategy, as it's been tagged. It's tower defense. Okay, just making sure.

For those looking for the music titles in the game, here's a compilation of all the songs identified (save for the defeat melody). Seems a majority of them are pieces composed by Schubert. The songs are listed along with the level they appear in.

Title Screen – Pyotr Ilyich Tchaikovsky: Second movement of Tchaikowsky's violin concerto

First Nazi Wave – Franz Schubert: Trio No. 2 in E-flat major, D.929 Op.100 (II. Andante con moto)

Mother Land – Franz Schubert: Ständchen, Schwanengesang D.957 No. 4

The Docks - Domenico Scarlatti: Sonata in D minor, K32

Bridge Alert - Franz Schubert: Das Fischermädchen, Schwanengesang D.957 No. 10

1943 - Franz Schubert: Variations on Trockne Blumen for Flute and Piano (Theme: Andantino)

Frozen Beach - Franz Schubert: Das Wandern, Die schöne Müllerin D.795 No. 1

Empty Fields - Franz Schubert: Aufenthalt, Schwanengesang D.957 No. 5

Main Base - Franz Schubert: Piano Sonata no. 5 in A-flat major, D.557 (III. Allegro)

Industry - Franz Schubert: Piano Sonata no. 5 in A-flat major, D.557 (II. Andante)

Last Blood of Stalingrad - Franz Schubert: Ständchen, Schwanengesang D.957 No. 4

I like the original more, but still a way cool game.