His specific style started getting shape a few years later, when he decided to integrate into his pieces samples from terrain recordings that he did during his trips throughout Bulgaria.
After putting some of his tracks online in social networks, his compositions were noticed by Henry Ernst, founder of the Berlin-based label Asphalt Tango Records.
[citation needed] The album “Opa Hey” quickly won the attention of the critics receiving many positive reviews, including in newspapers such as The Guardian and The Independent.
In December 2009 the album entered the prestigious World Music Charts Europe where it stayed for record-breaking 5 months and reached 3rd position in February 2010.
In March 2010 Nikola Gruev (sampling, programming) together with his colleague from the University Hristo Hadzhiganchev (guitar & keyboard), Alexandar Dobrev (clarinet) and Yordan Geshakov (bass) founded Kottarashky Live Band.
[2] Soon after the premiere of the album, Kottarashky & The Rain Dogs obtained their first professional music video to the single "Demoni", created by the world-renowned animator Theodore Ushev.
In a positive review of the album Opa Hey!, music critic Tim Cumming of The Independent wrote, "What you hear feels like a dislocated dream ride through the pungent soundscape of night-time Sofia.
"[4] Robin Denselow of The Guardian rated the album as 3/5 and wrote, "[E]ach of the 12 pieces here is constructed around a catchy, repeated riff, created not just from electronica, bass or keyboards, but from brass phrases, voices or strings.