Basically any upbeat song that reminds you to appreciate life in the middle of absorbing and applying theory. Anything from the Internationale to Red Army tunes to modern(ish) artists like Chumbawamba are allowed. Even Lofi.
Personal favorite of mine is Quand Fera-T-Il Jour, Camarade? by Mireille Mathieu. It's bittersweet, hopeful and resolute. Even if I don't speak French, I sometimes mumble to it.
Runner-up would be Solidarity Forever by Pete Seeger.
My kind of thread!
You mention "Quand fera-t-il jour", you might like Le Drapeau Rouge, great lyrics ("dare, dare to defy it, our great red flag, stained red with the blood of the worker")
I have a soft spot for Latin American songs, and they're particularly topical these days; check out Venceremos.
The Italians made one of the most radical and violent versions of the Warszawianka in the 70s and it absolutely does not fuck around with the lyrics.
Connolly Was There is superb in its hopeful message near the end (Oh Irish men, the day will come when workers one and all, will rise up on their bended knee and rally to the call, throw out the bosses' tyranny and shout from shore to shore, for a working man's Republic and for freedom ever more!). The final alteration of the refrain implies the spirit of James Connolly will watch benevolently from above as the Irish begin their new project of a worker's state.
Tearing up now writing this, thanks for this thread
Another one of my favorites, actually. Admittedly, I first heard of it from the same source, Kaiserreich. That game's OST is great.