"Closer" is the third single by Lacuna Coil from their album Karmacode. It proved not to be as successful as other singles most likely because of its more "pop" feel rather than the band's regular dark sound.
This song appears as a bonus track in the game Guitar Hero III: Legends of Rock. It is widely considered to be the easiest song to FC in the game, the only hard part being the chorus' three note chord sequence, but at such a slow speed it is very easy to master.
In the community, 'Closer' has become somewhat of a meme. Jokingly, the community refers to it as essentially impossible. So hard, that people have created an 'underchart', which would claim to make Closer easier, when they actually do the opposite and make the song a nightmare to even pass. Very few people have FC'd this 'underchart', the first person being TobeGH3.