Connect 4

Connect 4 — Pop Out

Four in a row, and the move that takes one back out.

The classic game only ever adds discs. Pop Out lets a turn be spent the other way: instead of dropping one in, you pull one of your own discs out of the bottom row, and everything stacked above it falls a slot. One column collapsing settles up to six slots at once, so a single pop can finish several lines of four — and they are not always yours. Pull a disc out from under your opponent's three and you hand them the round. If the same move completes a four for both colours, nobody takes it. A full board stops being the end of anything, because there are still discs to pull out from underneath. Pop Out is a toggle: turn it off and this is the game everybody already knows.

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Against the bot

It searches with alpha-beta minimax over both kinds of move, so it will pop a column open when that is the strongest thing on the board rather than only stacking. Its skill is a value between 0 and 1 rather than a label: on Easy it plays most moves at random, on Normal it thinks about most of them, and on Hard it searches every line it can reach and does not blunder. A harder setting means an opponent that looks further ahead, not a bigger board.

On one device

Two players taking turns at the same screen, first to as many rounds as you agree on, alternating who opens so nobody keeps the first-move advantage. The buttons above the board drop a disc in; the ones below pull one out, and they only light up over a column whose bottom disc is yours. Hovering a drop button shows you where the disc would land.

Online

Pick the name the others will see, look through the open rooms, and join one or create your own with a password if you want it closed. The host sets the mode and the length of the match, and starts once everybody is ready. Rooms run on a small relay that never learns what a board is — one player in each room referees, and every move is checked there before it happens on anybody's screen. There is a chat in the corner of the room, of the match and of the results, and if your opponent walks off a bot takes their seat so the game carries on.

Credits

• Music — PizzaDoggy
• Sound effects — RPG Essentials SFX by Leohpaz
• Font — Chewy, SIL Open Font License
• Made with Godot Engine 4.7