head to head
Oh...Sir!! The Insult Simulator asks more than Garry's Mod, and the gap is reads.

Reads · Light / Casual
Source-engine sandbox whose community modes range from building to social deduction.

Reads · Bluff & Deduction
Assembling insults from a shared random word pool while denying your opponent's combos.
Garry's Mod leans Reads (Light / Casual); Oh...Sir!! The Insult Simulator leans Reads (Bluff & Deduction).
Garry's Mod leans a little harder on execution, though the gap is small.
Garry's Mod
Varies by mode; base sandbox is undemanding
Oh...Sir!! The Insult Simulator
Picking phrases under a timer barely tests hands
Oh...Sir!! The Insult Simulator leans clearly harder on reads.
Garry's Mod
Social deduction modes like TTT involve humans
Oh...Sir!! The Insult Simulator
Versus humans, denying the words your opponent wants matters
Oh...Sir!! The Insult Simulator leans a little harder on variance, though the gap is small.
Garry's Mod
Hidden roles and player chaos in popular modes
Oh...Sir!! The Insult Simulator
The shared word pool deals random sentence fragments
Oh...Sir!! The Insult Simulator leans a little harder on optimization, though the gap is small.
Garry's Mod
Contraption building rewards systems knowledge
Oh...Sir!! The Insult Simulator
Combo and sore-spot scoring rules are learnable math
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.