My experience of go-related gatherings is that, when the players are bored of serious go play, they play a go variant - rengo, or one-colour go, or go on differently shaped boards. That is, something that feels like go, not just something superficially similar. Your games don't especially feel like go: they may be of general interest (in the same way that I am interested in xiangqi and backgammon and other non-go-related games), but you've altered the rules in a way that makes the feel of the game very different. Such a heavy penalty for the first capture makes most fighting completely impossible, and most invasions very easy, for instance. If there is good strategy and a deep and interesting game here, it's probably nothing like go.

Right. It's probably my fault not to have made this sufficiently clear before.

I've added a sample 9x9 Quench #3 game to my original post:

It seems the for #1 and #2 there is no reason to not make a new group every turn before you make the first capture. Creating the most groups gives the most flexibility for later on. Additionally very loose stones means that your opponent would be forced to capture earlier, putting him at a disadvantage.

Probably on smaller boards you'd want to play a bit thicker since captures would happen very late in the game though.

I was surprised by how go like version 3 is. It appears that one major biggest distinction is that it is usually bad to make the first capture in a ko shape, as long as your opponent's coin is heads up. Since ko is an integral part of the strategic depth of go, I think this has to be counted as a negative.

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Occupy Babel!

A similar but more flexible idea:

Once a player makes a capture for the first time, that player can't place any stones on enemy territories for the rest of the game.

(A territory is strictly defined as a maximal set of adjacent empty points which is bounded by stones of that color only.)

The disincentive to capture is much lower here.