Here's an interesting site with an extensive list of connect four programs.

entr0py: Currently, all the sites I regularly play at use an 8x8 board, as BrainKing does. I have played other sizes in the past, including 7x6; see here for a list of sites offering connect four.

hexkid: I've never heard of this Pro Line4 being played anywhere. Incidentally, in that game you linked to, I note that Jason does have a diagonal four in a row in addition to the horizontal five in a row.

Fencer: Two lines can disappear after a move in a corner which completes two perpendicular rows, so I had thought the same applied to parallel rows. The way it is now, sides of the board can become "blocked" and the game's dynamic aspect is reduced. Still, BrainKing is the only site to have this game, so there is no precedent to contradict your method, and maybe I'm just annoyed at losing. :)

Still, have you ever played Tetris?

In this Spider Linetris game, why is the A column remaining full?

I was thinking that the Line4 players on this site weren't very active, but then I realized I was wrong when I noticed this epic series of games between Jeckelchen and jeckel. Their playing styles have become so refined that they know if they should resign by the second move! Wouldn't this site be more interesting if all players were as busy?

Ah, I see Fencer has clarified that more than five win on the Hasami Shogi board.

ColonelCrockett: The rules for Pro Five in Line and Swap Five in Line explicitly note that exactly five must be placed in a row. Hasami Shogi may also follow this restriction, but the rules do not refer to such a situation.

ColonelCrockett: According to the rules, no: "The object is to place 5 or more pieces in a solid row..."

Hrqls: Yes

Hrqls: Yes, but the mirror strategy can prove successful on occasion, even against the best: http://brainking.com/en/ArchivedGame?g=760289&i=52

rod03801: If your offer hasn't been taken yet, go ahead and invite me.

rod03801: An example

I haven't been able to find a truly comprehensive resource for connect four information, so I've decided to start work on my own.
http://fourinarow.50webs.com

"Each player receives 16 disks of his own colour and 5 white disks." You would be forced to use wild pieces if the game went on long enough.

Anyone heard of CARAMBA 4?

See this site for some solved board sizes: http://www.cwi.nl/~tromp/c4/c4.html

I was white in this game with "John's Connect Four Playground," a "perfect playing connect-4 program" Its "12Kbyte database of all 8 ply positions" did not stop it from making a losing mistake on its second move.

1) d1 - a1
2) f1 - b1??
3) e1 - g1
4) c1*

No human expert would let me win in four moves, regardless of who started. What constitutes perfect play as black is subjective, of course, but that is exactly why humans are better at it.

Programs that can play connect four (6x7) perfectly:
4 in a row (http://www.fierz.ch/4inarow.htm), Mustrum(http://www.lbremer.de/mustrum_e.html), TitOT (http://corporate.skynet.be/bats/TitOT/), Velena (http://www.ce.unipr.it/~gbe/velena.html), and John's Connect Four Playground (http://homepages.cwi.nl/~tromp/c4/c4.html)...


But the purpose of games is to provide entertainment for human players. Therefore, computers will not discourage me from playing "solved" games. Only when connect four is solved for me (that is, when I know how to always play perfectly myself), will I abandon it.

Computers are not all so strong. Here follows a game I played with the program found at http://members.aol.com/shadows125/connect4.htm. Since there was no option for me to play second, I used the opening move a1, which is a proven loss for player 1.

BuilderQ vs http://members.aol.com/shadows125/connect4.htm

1) a1 - d1
2) d2 - d3
3) d4 - d5
4) f1 - d6
5) f2 - f3
6) g1 - c1
7) e1 - c2
8) e2 - c3
9) g2*

Since the program never learns from its mistakes, unlike a human player, you can go to that site and play all of my moves, and it will respond with the moves I have recorded.

Many people still enjoy playing the 7x6 board on other sites, despite its being solved, so I don't so why BrainKing shouldn't have it in addition to the 8x8.

Odd board heights are workable, but require revised strategies.

By the way, here's another variant:
CRISS CROSSING FOUR IN A ROW

What sort of "gravity" exists in this variant? Or can pieces always be placed in any of the 64 spaces?

Well, click here to see one possilbe web pattern.

Based on the example of Froglet's success, I wonder if the popularity of Spider Line 4/tris could be elevated through the use of pieces with a more thematic quality. Click here for an example of what I mean. :)

Can pieces left floating (unconnected to any edge or other pieces touching the edge) serve as bases to stack from?
Maybe the description of this board should be modified? :)

I would say black. Zugzwang generally forces white to be the one to complete the bottom row, enabling black to stack four vertically in the newly-created spaces at the top

No, it isn't mentioned in the rules, but thanks for the clarification.

As for a spider web shape... the spaces have to be a shape that can tessellate. Or is it the general shape of the board that we are talking about?

What happens? Does the restriction against playing on top of the last piece prevent the final column from being filled?

Are there any computer programs that play Spider Line4? I could do with a bit of practice. :)

Yes, but strategy would be completely changed. Maybe draws would become too common? Still, it's something to look into...

I'd also like to see regular Line4 on a 9x9 board. :)

Does anyone know of a game site offering the variant Euro 4?

Rules: The variant is played on a 7x7 board. The first piece must be placed in the center; subsequently each new piece can be placed in any space orthogonally adjacent to an occupied space. The first player to get four in a row wins. The player who moves first shall be refered to as White, while the second player is Black.

The move tree below details how White can win in, at most, eight moves. Most of Black's moves are forced, and where there are options, each is played to conclusion.

1. d4 c4
2. d3 ...
Black can do either d5 or d2.

With 2. ... d5
3. d2 d1
4. c3 ...
Black can do either b3 or e3.

With 4. ... b3
5. e3 f3
6. f2 c5
7. e2 g2
8. c2*
1-0

With 4. ... e3
5. b3 a3
6. b4 e1
7. b5 b6
8. b2*
1-0

With 2. ... d2
3. d5 d6
4. c3 ...
Black can do either b3 or e3.

With 4. ... b3
5. e3 f3
6. e5 b2
7. c5 b5
8. f5*
1-0

With 4. ... e3
5. b3 a3
6. e5 b2
7. c5 b5
8. f5*
1-0

I'll post the complete game move tree once, and if, I can find it.

No, I meant that a piece could be placed anywhere that was orthogonally adjacent to the position of another piece.

Yes, it would be an odd-sized board, like in the pente games, with only orthogonal sticking.

Once I have time for it, I'll do a little study to prove the first player's advantage.

Maybe a variant in which pieces could stick to the sides of other pieces would be interesting.

Perhaps it could be that pieces would only stick to each other, and not to any side. White's first move would have to be in the center, and play would build out from there. Some sort of restriction would be needed to prevent it being an easy win for the first player, though.

Maybe we should take a step back and remember that 8x8 line4 has not been solved yet. Neither player has been proven to have a sure win.

Perhaps two-game matches are the fairest way? But they seem superfluous between players of widely disparate skill levels.

Consider the following, which is based on all line4 games played at BrainKing.
Statistics
White won 7614 (51.11 %)
Black won 7201 (48.34 %)
Draws 81 (0.54 %)
I don't think most players below the ceiling would find it much help to play as black against those above the ceiling.

Yes, the 6x7 board is a first player win. I used to think that applied to the 8x8 board as well, and discussed the matter with grade1teacher, who thought otherwise. However, I have now joined the consensus that I discovered exists among the top players here: black has the advantage on the 8x8 board. The extra column negates much of 6x7 theory, and so far I can see no win for white.

www.farfarfar.com has some good (though not error-free) information regarding line4. It also has a reasonably good program you can practice against, and most importantly, a number of links to other sites related to line4.

Unlike all the other line4 varations available on this site, linetris games are not limited to 32 moves. Indeed, they could theoretically last indefinitely. So, what is the record for longest game of linetris?

By the way, with all due respect to Tactician, I think this board should have a moderator who is online more than once a year.

I'm surprised that there is so little discussion on this board. Aren't there many line4 players on this site?
Anyway, I think that in line4 (all line games, in fact) the winning rows should be highlighted.