How to play
The rooftop is a 5 × 5 grid of squares, all at ground level to start. Each player has two builders. First you each place both of your builders on any empty squares.
On your turn, do two things with one of your builders. Move it one square in any direction, diagonals included. It can step up one level at most, but can drop down any number. Build one level on any square next to where it now stands (including the square it just left). Towers go up to level 3; building on a level 3 puts a dome on top, and nobody can stand on a dome.
Step up from level 2 onto level 3 and you win straight away. If neither of your builders can move at the start of your turn, you lose.
Tips
Keep at least one builder high: a builder on level 2 next to a level 3 threatens to win, and your rival has to spend their build on a dome to stop it. Two threats at once can’t both be capped. And watch where you build: a level 2 next to your rival’s builder on level 1 is a step up for them, not just for you.