Some scholars say that the Welsh name Gwyddbwyll originally meant the same tafl game played in Ireland under the name Fitchneal. Like the latter, the Welsh name has confusingly come to mean Chess in modern Welsh. Most other scholars however disagree that this is the same as the Irish game which was played on a 7×7 grid.

Two opinions exist among those who maintain that the name Gwyddbwyll refers to a purely Welsh game. The Wikipedia Gwyddbwyll page describes chess at the top of the page, and this game below, referring to it as Gwyddbwyll Geltaidd to avoid confusion. It notes however that the game is properly called merely Gwyddbwyll, the longer name meaning merely "Celtic Gwyddbwyll". This website also shows the initial set-up and gives a brief but incomplete description of the game in Welsh. The game according to this opinion is played on 9×9 grid and the object for the defending player is to get the king to a corner. Rules are otherwise presumably like Brandubh.

The alternative opinion that the game was played on a 7×7 grid is described at Celtnet. The initial set-up described there may be slightly speculative, but again it is believed that the other rules not described there were identical to Brandubh.