Start. The board starts empty. This is a game of placement only, with no movement or capture.
Object. To be the first to make a troika – that is, a line of three pawns of your own colour in a row, whether horizontal, vertical, or diagonal. They need not be adjacent, but may be any distance apart and lying at any angle relative to the board. For example, this illustration shows Black winning with the line 8-12-10.
Play. You each in turn place a pawn of your own colour on the board. The first pawn may be placed anywhere, and each subsequent pawn must be placed en prise to the previous one. You win the game by making a line of three, as described above.
You may not immobilise your opponent, and must therefore retract any move that allows of no legal continuation. If neither of you has made a line of three when all 16 pawns are down you may declare the game a draw.
Alternatively, play continues with each of you in turn removing one of your pawns from its current position and placing it en prise to the previous one as usual. Continue till one of you eventually wins or you both die of boredom.
This is one of my favourite Katarenga games. It's surprisingly intricate and tricky. (I've just confirmed that 'tricky' is ultimately cognate with 'intricate', so, in a sense, that comment was tautologous.) Beginners often lose before placing more than four or five pawns, and even experts have never yet, in my experience, got as far as all 16 pawns on board. Indeed, as a problem, you might try continuing this game (playing as both opponents) in such a way as to prevent either from making a troika. It's a bit like the eight-queens-on-a chessboard puzzle.
Pawns move from red like a rook, from yellow like a bishop, from green like a knight, from blue like a king and not beyond the next square of the colour it started from. It may not jump or land on another pawn except to capture one of the opponent's. (Troika is a game of placement only, but rules of movement also govern placement.)