PROTO is launched on June 10, 1992 and can be played within Lotto slips.
It has 6 main and 2 extra prize categories (+3, -3 from last digit).
The initial column price at 100 drachmas (or 0,30€). 

On November 12,1997 an independent PROTO play slip is introduced and the game is revamped.
New winning categories are established (those whose number agrees with the first 6, 5, 4, 3 and 2 digits of the drawn number) and the 2 extra prize categories are abolished.

Fixed winnings for prize categories II to VI are established on January 26, 2009. 
Furthermore, a new and redesigned play slip is in place, offering more gaming options as well as the ability to participate in consecutive and future draws.
Column price changes to €0,50.

In April 2023, opaponline.gr is launched, offering players the chance to submit their slip online, through opaponline.gr and mobile app.