Something about Mayday.

Mayday is a festival dedicated to more accessible forms of electronic dance music.

Despite the fact that artists such as Jimi Tenor (famous live act on a vacuum cleaner) and Aphex Twin himself have played there, techno purists don't appreciate it much and avoid the festival and its dedicated compilations by a wide margin. They think that techno from Tresor (Jeff Mills, Robert Hood, Joey Beltram, Cristian Vogel, Neil Landstrumm) is the only real techno and that Mayday is commercial for the rich youth. In my opinion the tracks on Mayday compilations are simply more accessible and easier to listen to than most underground techno, but whether that's a disadvantage or an advantage let's each judge for themselves.

The styles of the compilations evolved over time. At the beginning there was a lot of strong sounds (Infidus, Army Of Darkness), then came electro and acid (Beroshima, Genlog, Miss Djax) then trance (Sunbeam, Yves De Ruyter) then drum & bass (Bassface Sascha, DJ Apollo, DJ Sebel) and even big beat (!) (Stretch N' Vern). 

The last good compilation from Mayday was "Worldclub" from 2006. After that there was a lot of monotonous tech-house or banal hardstyle and EDM and it wasn't the same anymore.

In 2013 an anniversary compilation "Mayday - The Complete Rave Generation" was released, containing the best old-school rave tracks that people born in the 80s probably remember from their youth.