I agree, but I have no clue what you want. :D I've spent some time in Salzburg, Berlin and Bochum and it was quite similar but instead of parek a pivo there was bratwurst und bier. There are grafitti in Prague and also people doing interesting things. I've recently seen that near Vltavska metro station there is an interesting spot for parkour. Letná park (metronome/stalin statue) is legendary spot for skating. Then there is Mystic skate park Štvanice. I live in Prague 6 and there are many places such as Ladronka (workout, inline skating, running, tennis, beach volleyball, discgolf, ...). Na Fialce there is agility (cynology), BMX park, cyclocross, motocross, golf. Those two are more casual, but you can definitelly meet a subculture when visiting Letná or Mystic.