head to head
Spelunky asks more than Skul: The Hero Slayer, and the gap is variance.

Execution · Practiced Mastery
Head-swapping action roguelite where each skull is a new moveset.

Execution · Twitch Chaos
The original procedural platformer that codified the modern roguelike action loop.
Skul: The Hero Slayer leans Execution (Practiced Mastery); Spelunky leans Execution (Twitch Chaos).
Same score on execution - which means the number cannot separate them. The difference is in what each one asks of you.
Skul: The Hero Slayer
Action platforming with skull swaps demands precise combos.
Spelunky
Tight platforming and whip control under constant threat.
Spelunky leans a little harder on reads, though the gap is small.
Skul: The Hero Slayer
Enemy AI is fully scripted.
Spelunky
Enemy AI is scripted; no adaptive opponents.
Spelunky leans clearly harder on variance.
Skul: The Hero Slayer
Skull and item drops swing runs.
Spelunky
Procedural caves and item rolls shape every run.
Same score on optimization - which means the number cannot separate them. The difference is in what each one asks of you.
Skul: The Hero Slayer
Skull synergies and boss patterns reward study.
Spelunky
Hell route and shortcuts reward solved knowledge.
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.