notes:

1) at 11:02 I talk about X having a forced win, but I messed up the editing and X actually has a forced win at 10:59, not 11:02. By 11:02 they have messed up and the game is winning for O.  

here's the forced win: go to 10:59. See the rightmost X? Place an X right above it (call this position A) and then another adjacent X, to the right and up (call this position B). That creates a threat, and O cannot create their own threat while blocking that threat. So X gets the next move, and places an X right above position A and also another X right below position B. This creates 2 threats at once, X win.

2) Slight mistake at 5:51, when X blocks O's threat they actually create a weak threat of their own that I didn't catch. However this doesn't affect anything, and O still wins. It just takes a couple more moves than shown in the video

3) thank you for all the ideas! (like penrose tiling, removing the center hexagon, etc.) you will see them in part 2

4) hexagonal tic tac toe stream tomorrow playing with viewers, also I have some other ideas I want to test out

seems like the X has an advantage because it goes first. i think O should go first

2:35 “Draw given perfect play, which isn’t very hard.” Congratulations, you’ve made hexagonal tic-tac-toe!

“Nobody wants to play 6-in-a-row with me” yes we do 100%

"Hexagons  are the bestagons"

2:35 i mean normal square tic-tac-toe isn't really much better in this aspect

Why don't we just remove the middle hexagon??

There's something nice about the best 'N in a row' on a hexagonal grid being 6 in a row.

You compound rules on top of existing rules but never consider to remove them once the underlying condition that made not having them problematic was also gone.

For instance, you gave each side double moves to avoid unfairness in a closed board, but as soon as it was opened up, and the win condition was expanded, the double move caused more problems than not fix problems anymore.

You should have returned to single moves.

In order to even out the first move advantage, make the center tile universal for both players.

Hexagonal Tik-Tac-Toe you say?
20 missed calls from CGPGrey.

0:53 who cares, it IS interesting

Just drop the 2 pieces per turn rule after switching to the infinite grid. Then even 5-in-a-row should be playable.

Just throwing this idea out there: In all these X-in-a-row games, you could solve the first turn advantage problem by letting both players play simultaneously. Both players independently and secretly choose a space, then both place their mark where they chose. If they choose the same, then the space becomes blocked off and neither player gets it, ever. Or as another variant, if both players choose the same, both players get their mark there.

I have not thought through the implications of this. You seem like the kind of guy who enjoys that anyway.

Okay, hear me out!
3 players...

In gomoku -- which is connect 5 on a square grid -- the fairness rule used in tournaments is called swap2. The first player puts down 2 Xs and 1 O wherever they want. The second player decides which symbol to play as for the rest of the game. The general class of games is usually called m,n,k-games, for an m-by-n board requiring k in a row. Gomoku is the (15, 15, 5)-game.

8:32 "there are actually 3 threats here but i somehow missed one"- ur welcome

2:11 my first thought is the middle hexagons gone

0:30 I thought “solved” means all potential plays can be accounted for, and with PERFECT playing, we know which player will win or if it is inevitable for a draw?

chess at the highest levels tends to draw a lot. so giving white a slight advantage makes them more inclined to push for a win instead of settle for a draw, so it's more entertaining / fun. players play white and black close to an equal amount of times to balance this out.

also at lower elo, the first move is far less significant, but few players want to prepare for the first move being 1. h4 or something silly like 1. Na3, so it's probably better to not use pie rule, even though it's slightly less fair

EDIT: apparently h4 and na3 are actually really terrible moves and give black a massive advantage, e3 is a lot more 'equal'

2:24 Yavalath is basically tic-tac-toe (or Connect 4) on a hexagonal board. It solves this problem easily with one extra rule: You win with 4 in a row, but lose with 3 in a row. This slows down the game, gives you two win conditions and results in more interesting play.