TL;DR: Very big Tic-Tac-Toe, 5 win, not 3

Overview
N&C Infinity is an online version of what Noughts and Crosses (or its smaller, boring alternative Tic-Tac-Toe) should be. Normally players are limited to what size their paper offers. This game offers infinite playfield without the need to use any paper.
Also, you may compare this game to Gomoku, which is very similar, but has a different start to compensate for first player advantage and ends when a player scores first time with exactly 5, no more pieces in a line.
The game starts when you create a game by clicking the create game button, filling in all The Server needs to know and then goes on forever. Unless you set a point at which a player wins by scoring a chosen count of points. If you want to add the old paper feeling, you can also limit the size of the playfield. Then you choose if you want other players to be able to spectate your game live and if you want to send an immediate invite for the player you are playing with.
Remember the name of your game, because you can at any moment join back and keep on playing.

The game starts
First goes the second player. Sounds logical. You created the game, you invited the other player and a guest is always first, right? You draw your nought or cross by clicking the field you want it to be at. Last move made is highlighted with an orange background and is 'jumpable' to using the button above the playfield. This way it's fair if someone makes a move off your screen.
The turn swaps to the other player once made and if you want to know who's turn it is, just look at the colorful glow behind their photo. And yes, you can change your color to your favourite one in the profile editor.

And goes on
A player scores once they align 5 of their pieces in a straight line - horizontally, vertically or diagonally. You can also score using already crossed out pieces, but you can cross them only once in each direction. 6 in a row don't count as 2 points. If the game was not set to be neverending, it ends once one of the players achieves the desired amount of points.

Some technical stuff
If 6 or more uncrossed pieces in a line are uncrossed, the group of five most to the left is preferred by The Server. When aligned vertically, the highest one is chosen and crossed.
If The Server and a client desynchronize, an error is raised on the client and it also has to leave the game as further play is not possible. User can rejoin the game right away. If something goes horribly wrong, The Server holds the authoritative copy of the game and no invalid moves will ever be confirmed (unless something breaks).
Autosave is set to 60 seconds long intervals.

Good luck and have fun!