Diablo 1 has a single town, but there is a similar "new environments" part of the gameplay since as you go into the dungeon it changes. So theres the church ->

Diablo 1 has a single town, but there is a similar "new environments" part of the gameplay since as you go into the dungeon it changes. So theres the church -> catacombs -> caves -> hell. Though the whole game is maybe just a little longer than Act 1 in Diablo 2 (but its tough to say because its a much slower paced game).