Here is the full list of all 12 RFLEX achievements.
First death.
Beat 'Amusement'
Beat 'Challenge'
Beat 'Addiction'
Beat 'Lifestyle'
Beat 'Death-wish'
Used epileptic mode.
Beat 'Amusement' while Drunk
Beat 'Challenge' while Drunk
Beat 'Addiction' while Drunk
Beat 'Lifestyle' while Drunk
Beat 'Deathwish' while Drunk; pass out