A fixed version of Pirate Doom! for newer GZDoom versions. Tested with stable GZDoom versions up to 4.7.1 (as of 28th December 2021).
Firstly, I take no credit for this work as all I've done is fix the Pirate Doom! mod to work with newer (including the latest) GZDoom versions. Pirate Doom! was created by Arch and the download contains all of the files from his download, with the necessary credits, the only difference being that it includes the fixes that I've made to get it working on new GZDoom versions.
The first fix was to get it to actually run. The problem here was with the dashsound actor not being a child of an inventory type. As this actor was effectively a dummy actor (containing no code), all I've done is change it to a child type of CustomInventory, and the game now loads up fine.
The second fix was to rename the map actor to map1 so as to prevent the duplicate name entry. I don't think this was causing any issues running it but the warning is now cleared.
The third fix I implemented was for the overbright smoke sprites that sometimes showed up (e.g. when firing the cannon (rocket launcher replacement), when a Lost Soul is destroyed, when using dynamite, smoke over lava, etc.) as these were displaying as solid white on my machine (I've seen it be solid white and solid cyan on some gameplay videos). On digging around in the code I found that these overbright white sprites were the ones being called from smoke4, where I noticed that the alpha flag for the sprite had a value of 128 (when it should be in the range of 0-1), so I changed this to 1 and now the smoke displays correctly.
Update: 27/03/2017 (I'm going to call this version 1.8.2 as it is my second set of fixes on Pirate Doom! v1.8).
Fix number four. It came to my attention that there was an issue with one of the MIDI files in the game - MOJO.MID. When using FMOD EX the music would play but the volume was very high and a lot of what sounded like drum cymbals and snares were playing constantly causing a kind of white noise over the top of the track. Lowering the music volume in game would lessen this, whilst when using OpenAL the track would not play at all. I can only guess that the file was corrupted in some way with erroneous instrument/note data. As such, I've implemented a new fix to replace this one music track. On identifying MOJO.MID as the Witchyworld track from Banjo-Tooie (thanks to the credits in Arch's original Pirate Doom! archive and some time spent listening to soundtracks on YouTube) I then saved the track, cut out the relevant part and matched the track length to get the same speed as intended for the mod and saved it in OGG format (I can't save as MIDI as I don't have a MIDI editor). So now the House of Mojo level plays music nicely.
Fix number 5. I've exported and re-saved all of the OGG format sounds, so now the missing sounds issue (when using FMOD EX for the sound system) should be resolved. I've not noticed any missing in my testing, so the chaingun, bottles smashing, Imp swords hitting walls, various lines of speech spoken by pirates, ammo pickups, etc. are all now working correctly. NOTE: As recent builds of GZDoom no longer use the FMOD EX sound system, this fix is no longer needed as the OpenAL sound system didn't have this bug.
Lastly, fix number 6. I noticed that some of the setmusic commands in the level scripts contained three parameters, but that third parameter is listed as unused and is not recommended to be used (see here Zdoom.org) so I've removed it. There were only a few instances of this.
Update: 29/03/2017 (v1.8.3) - I've fixed a typo in the epilogue text credits: itens => items
As I've now finished my playthrough of the mod I'm not intending to update the file any further unless anyone can point out any bugs/issues that I'm able to fix.
Note: 22/10/2017. With the more recent versions of GZDoom having removed FMOD EX and only using the OpenAL sound system, the missing sounds issue should no longer be a concern for the official release of Pirate Doom! However, the other fixes I've made, such as getting it to run, clearing the warning messages, fixing the one corrupted MIDI file, typos, etc. are still all valid fixes.
Update: 10/08/2018 (v1.8.4) - Removed the checks for vid_renderer=1 in the ACS scripts for the first two maps of the mod as this cvar is now defunct and it was causing some messages to show up on screen and then killing the player on the second map for not changing the renderer. This is completely obsolete with GZDoom 3.4.0 and above.
Update: 28/12/2021 (v1.8.5) - Renamed sprite SHT2EO (for the super shotgun reloading animation) to SHT2P0, and updated the TEXTURES reference to SHT2E0 to use SHT2P0 as a patch, in order to fix the missing sprite issue caused by the game_widescreen_gfx.pk3 file that GZDoom now comes with.
Extract the archive and use GZDoom to load Pirates!.wad with the Doom 2 IWAD.