Hi Composer here, The tone of melody it kinda mix between Undertale Spider dance theme..ish(that why you felt similar)and Some another game boss fight as well (Feel like that has Arpeggio melodic mix with Phrygian flavor for horror theme).
Also If you play pass through near ending, You can that the song can be separate into three part (Phase 1 Boss fight, Transition between phase 1 and phase 2, and the Phase 2 fight) which kinda typical for Boss fight OST.
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