As it has been showed, 2D games have the potential to be timeless, specially if played on a proper CRT setup. Some examples off from the top of my head.
Last Blade 2 (NeoGeo, 1998).
http://i.imgur.com/KHa46.jpg
Garou Mark of the Wolves (NeoGeo, 1999).
http://i.imgur.com/EKShp.png
Metal Slug 3 (NeoGeo, 2000).
http://i.imgur.com/N9yar.jpg
Warzard / Red Earth (CPS3, 1996).
http://i.imgur.com/5MQit.png
DoDonPachi (Cave 1st Gen Hardware, 1997).
http://i.imgur.com/NbALW.png
ESP Ra. De (Cave 1st Gen Hardware, 1998).
http://i.imgur.com/MnZIf.png
Super Metroid (Snes, 1994).
http://i.imgur.com/ITZT7.jpg
Chronno Trigger (Snes, 1995).
http://i.imgur.com/Fse3i.jpg
Castlevania Symphony of the Night (PlayStation, 1997).
http://i.imgur.com/18Q2r.jpg
Astal (Sega Saturn, 1995).
http://i.imgur.com/IEbgm.jpg