Kris Burm's Riomino (or Tashkent Domino) is played with 25 identical dice that look like this:

The actual rules are as follows.

1. Each player rolls 12 dice that then serve as their "dominos" (once a die is rolled the face showing up must stay up for the remainder of the game).
2. The last die is rolled and placed between the players, who then take turns placing their "dominos" like in actual dominoes. The polyomino thus formed must always fit within a 5×5 grid.
3. A player who cannot move loses.

Now when I took this game to Friday Night Magic yesterday with just the dice and no instruction manual, I forgot rule 1 above and inadvertently made the game of No-Luck Riomino:

1. The dice are common property. Starting from an empty playing field, each player takes turns to place a new cube in any orientation they like, but still obeying the dominoes and bounding box restrictions in rule 2 above.
2. A player who cannot move loses.

No-Luck Riomino is an impartial normal-play game, so one player has a winning strategy – but who?

Kris Burm's Riomino (or Tashkent Domino) is played with 25 identical dice that look like this:

The actual rules are as follows.

1. Each player rolls 12 dice that then serve as their "dominos" (once a die is rolled the face showing up must stay up for the remainder of the game).
2. The last die is rolled and placed between the players, who then take turns placing their "dominos" such that adjacent dots match (no other restrictions). The polyomino thus formed cannot take up more than five squares in either direction.
3. A player who cannot move loses.

Now when I took this game to Friday Night Magic yesterday with just the dice and no instruction manual, I forgot rule 1 above and inadvertently made the game of No-Luck Riomino:

1. The dice are common property. Starting from an empty playing field, each player takes turns to place a new cube in any orientation they like, but still obeying the dominoes and bounding box restrictions in rule 2 above.
2. A player who cannot move loses.

No-Luck Riomino is an impartial normal-play game, so one player has a winning strategy – but who?