A whiteboard with markers (or sheets of paper)
This one is best for teams, but you could do it individually depending on numbers
This can be inside or out
One team will be Os and one will be Xs and they will earn the right to place their symbol in each of the 9 squares of a three by three grid. Three symbols in a row horizontally, vertically or diagonally will be a win. In the case of a draw, points go to the team with the most symbols.
Each square is earned by playing a game of Lumpy Flat Pointy. In this game opponents will choose to reveal either a closed fist (lumpy) a flat hand (flat) or two splayed fingers (pointy). In each battle for a square, pointy beats flat, flat beats lumpy and lumpy beats pointy (as a way of deciding things, this could really catch on).
Each team chooses a first player to enter battle and a new game is played for each square going from left to right, top to bottom. A draw skips that square. When bottom right has been decided you return to each skipped square in order. The game stops as soon as there is a winner or the board is full.
If a player wins two squares in a row, they must switch out with a teammate, if there are two draws in a row both players must switch out. Other than that players can switch at any time.
Scoring is, as always, completely arbitrary, you can award whatever points you want for a win or a draw. Decide how you wish based on the number of teams.
If there are more than two teams you can decide matchups randomly or play a round robin tournament.
I did at one point institute a rule where if there is a draw in one of the two squares I had pre-determined, the active players only would receive a bonus point.