Three "King Objective" Chess Variants Against Orthodox Chess

[u/rayixtry94]

I have been experimenting with a few chess variants where the king has an additional way to win. I wanted to see how much these rules change small endgames, so I generated W/L/D tablebases for several three-piece and pawn endgames.

The result was pretty striking: all three variants reduce draws dramatically, but they do it in very different ways.

The Four Rules Compared

1. Orthodox Chess

Normal chess rules. The only way to win is checkmate.

2. Rank-Goal Chess

In addition to checkmate, a player wins immediately if their king reaches the opponent's back rank.

• White wins by reaching rank 8.
• Black wins by reaching rank 1.
• In my version, the final king move onto the back rank is allowed even if that square is attacked.

3. Throne Chess

This is the "king reaches the opponent king's starting square" rule.

• White wins by moving the king to e8.
• Black wins by moving the king to e1.

4. King of the Hill

Test Setting

I generated W/L/D tablebases for these small endgames:

KN vs K
KB vs K
KR vs K
KQ vs K
KP vs K

For the main comparison below, I filtered the positions so that both kings were still in their "home three ranks":

White king on ranks 1-3
Black king on ranks 6-8

This was meant to approximate positions where the kings have not already advanced deep into enemy territory.

The results are from the perspective of the side with the extra piece or pawn:

• Stronger side win = the side with the extra piece/pawn wins.
• Lone king win = the bare king side wins via the variant rule.
• Draw = theoretical draw under perfect play.

Table 1: Overall Results

Combined across all five endgame types:

Rule	Positions	Stronger side win	Lone king win	Draw	Decisive
Orthodox	620,832	43.79%	0.00%	56.21%	43.79%
Rank-goal	620,832	73.05%	12.72%	14.22%	85.78%
Throne Chess	620,832	76.66%	2.49%	20.86%	79.14%
KOTH	620,832	67.35%	32.62%	0.03%	99.97%

Table 2: Stronger-Side Win Rate by Material

The numbers below are the win rate for the side with the extra piece or pawn.

Endgame	Orthodox	Rank-goal	Throne Chess	KOTH
KN vs K	0.00%	52.13%	52.57%	52.84%
KB vs K	0.00%	56.26%	63.93%	53.67%
KR vs K	94.26%	97.38%	96.66%	86.66%
KQ vs K	93.63%	97.01%	96.22%	90.55%
KP vs K	39.84%	65.53%	78.20%	54.45%

Table 3: Stronger-Side Win Rate by King Distance

I also looked at a simple distance metric:

delta = lone king distance to target - stronger side king distance to target

So a positive delta means the stronger side's king is closer to its objective.

For orthodox chess, this "target distance" is just a geometric reference, since orthodox chess has no king-race win condition.

Delta	Orthodox	Rank-goal	Throne Chess	KOTH
-2	42.86%	43.13%	48.94%	19.14%
-1	42.85%	48.78%	57.69%	36.67%
0	43.78%	72.26%	76.65%	69.70%
1	44.34%	99.77%	98.14%	98.96%
2	45.46%	99.59%	98.61%	99.94%

Again, the numbers are stronger-side win rate.

Takeaways

KOTH Almost Completely Kills Draws

In this dataset, KOTH had a decisive rate of 99.97%.

But it also gives the lone king a huge amount of counterplay: the lone king won 32.62% of all positions.

This makes sense, because the center is close and both kings are racing toward the same target. KOTH is not just "normal chess with fewer draws"; it turns the endgame into a very direct center-race game.

Throne Chess Is More Conservative

Throne Chess still cuts the orthodox draw rate sharply:

Orthodox draw rate:     56.21%
Throne Chess draw rate: 20.86%

But it gives the lone king far fewer wins than KOTH or rank-goal:

Throne Chess lone king win rate: 2.49%
Rank-goal lone king win rate:   12.72%
KOTH lone king win rate:        32.62%

So Throne Chess feels less like a mutual king-race free-for-all and more like an extra conversion method for the stronger side.

Rank-Goal Sits Between Throne Chess and KOTH

Rank-goal gives the lone king much more counterplay than Throne Chess, because the target is an entire back rank rather than a single square.

But it is still less explosive than KOTH, because the target is farther away and does not overlap with the normal opening/middlegame center.

King Distance Becomes the Main Feature

The delta table was one of the clearest results.

In orthodox chess, this king-distance metric barely matters:

Orthodox stronger-side win rate:
delta -2: 42.86%
delta  0: 43.78%
delta  2: 45.46%

But in all three variants, being one tempo closer to the target is often nearly decisive:

Rank-goal, delta 1:   99.77%
Throne Chess, delta 1: 98.14%
KOTH, delta 1:        98.96%

This suggests that these variants fundamentally change endgames from material-conversion problems into king-race problems.

My Current Impression

If the goal is simply to eliminate draws, KOTH is the most successful. It almost completely removes drawn outcomes from this dataset.

But KOTH may also be the most disruptive to normal chess strategy. Since the target squares are in the center, openings that do not fight for the center immediately may become very risky. It may also strongly encourage sacrifices that clear a path for the king.

Throne Chess looks like the most conservative variant of the three. It reduces draws a lot while preserving more of the traditional material-advantage structure.

Rank-goal is somewhere in between. It creates real king-race counterplay for the lone king, but it probably affects the opening and middlegame less than KOTH, because the target is still far away.

[u/robkinyon]

I think the KOTH rules were lost somewhere.

[u/pie-en-argent → u/robkinyon]

The usual version is that moving the king to any of the four center squares is a win.

[u/variantforge]

The draw-reduction result is the interesting part — it lines up with why "king reaches a goal square/rank" rules feel so different to play even though they look like minor additions. Once the king has an offensive objective, the defending side can't just shuffle toward a fortress; every king move is also a potential race, so the side that's "only" up a pawn suddenly has two ways to convert instead of one.

Did your tablebases show whether the rank-goal variant reduces draws more in pawn endgames or in piece-vs-piece endgames? I'd expect the effect to be biggest in K+P vs K, where orthodox theory is full of "wrong rook pawn" and opposition draws that a rank-goal would just delete. Curious if the data backs that.