Learn Polish: Sukces zależy od tego, czy rollercoaster jest emocjonujący. - Success depends on whether the rollercoaster is thrilling.

In Polish, a preposition like od cannot directly attach to a conjunction like czy. It needs a noun or a pronoun. When you want a preposition to introduce an entire indirect question, you must use the pronoun to as a "bridge." Because the preposition od always requires the genitive case, to declines into tego.

Could we drop od tego entirely and just say Sukces zależy, czy...?

In standard Polish, no. The verb zależeć (when it means "to depend") strictly dictates the use of the preposition od. While you might occasionally hear native speakers drop the preposition in very casual, fast speech, writing or saying just zależy czy is grammatically incorrect. You must use the full zależy od tego, czy structure.

Emocjonujący looks like a verb form. What exactly is it?

It is an active adjectival participle, which is essentially a verb acting as an adjective. It is formed from the verb emocjonować (to thrill or to excite). By adding the ending -ący, it translates to "thrilling." It declines exactly like a standard adjective, which is why it takes the masculine nominative ending here to match rollercoaster.

Is the English loanword rollercoaster declined like a normal Polish noun?