Practice Mode (explained within!)
This could allow players the chance to improve their own knowledge on selected (unlocked) lists without having to wait for the list to be randomly selected in-game for matches.
In this game mode opponents would not need to be selected for the player, as it acts as a sort of ‘sandbox mode’, whereby a list (and maybe even letter?) can be selected by the player at no in-game or real life currency cost.
I understand how this feature may not align with the Scattergories vision, which is why I might suggest something like a 1 hour cooldown period on these practice games. This ensures players continue versing online opponents (as opposed to taking this proposed cost-free feature for granted), therefore likely having the effect of leaving players wanting, and receiving, more playtime. Win-win.
And then maybe in a future update, a new in-game prize could be introduced that acts as a key to unlock extra free-practice rounds, which would essentially negate the cool-down period of games for those lucky enough to win this prize.