DevilutionX is open source, reverse engineered version of Diablo.

Diablo is an action role-playing hack and slash video game developed by Blizzard North and released by Blizzard Entertainment in January 1997.

Set in the fictional Kingdom of Khanduras in the mortal realm, the player controls a lone hero battling to rid the world of Diablo, the Lord of Terror. Beneath the town of Tristram, the player journeys through sixteen randomly generated dungeon levels, ultimately entering Hell in order to face Diablo.

The Amiga port was created by Artur Jarosik and Marlon Beijer. ASM & AMMX optimization by Samuel Devulder. It is based on https://github.com/diasurgical/devilutionX contributed by various authors.

DevilutionX.lha

If you don’t own a legal copy of Diablo game you can try Shareware version:
DevilutionX-Shareware.lha