Learn Russian: Мальчик бродит по туманному парку, словно он привидение. - The boy wanders through the misty park, as if he were a ghost.

Conjunctions of hypothetical comparison like словно, как будто, and точно do not strictly require the subjunctive mood in Russian. When describing an ongoing state or action, you simply use the present tense. Here, it is a verbless clause, он привидение, literally meaning 'he is a ghost.'

Could I use как будто instead of словно here?

Yes, they are interchangeable. Словно and точно sound slightly more literary or poetic than как будто, which perfectly fits the eerie mood of a misty park, but the grammatical function and meaning are identical.

Why is туманному парку in the dative case?

The preposition по takes the dative case when it describes movement around, along, or through a surface or area. Since the boy is wandering through the space of the park, по triggers the dative forms туманному парку.

Why use the verb бродит for wandering? Is it a verb of motion?

Yes, бродить is the multidirectional verb of motion for wandering or roaming on foot. Wandering is inherently aimless and involves moving in various directions, which makes this multidirectional verb the exact right choice instead of a unidirectional one.