The Trail is a Dungeon Master Mod. It is semi-linear and closer in tone to Dungeon Master 2 than the original, though it uses the RTC source port and so the DM1 engine.
It is set in the Dungeon Master universe (If you're familiar with it, you'll see the links) and has some crossover with characters, spells, etc...
The Trail is a Dungeon Master mod set within the DM universe. As mentioned in the summary, it is closer in tone to DM2 than the original, is semi-linear, but uses a DM1 engine.
I put out this mod some time ago on a DM forum (dungeon-master.com) with Part 1 being around five years ago and Part 2 around 2ish (I think), and a while back someone said "You should get this on ModDB" and I thought "Yeah! That's a good idea" then promptly forgot about it. So upon remembering, here it is.
This is accessible for any fan of old-school RPGs, but knowledge of Dungeon Master spells is assumed (being in the DM universe), but if you're not in that boat... a png file is provided with all of the rune names and spells from both Dungeon Master and Chaos Strikes Back. There are further spells and items, but they are exclusive to this particular mod and can be found within the game.
I would recommend reading the README file and taking a look at the DM&CSB Spells.png even if you are familiar with DM (they're very short).
For anyone familiar with Dungeon Master source ports, the RTC files can be found in the 'modules' folder if you want to move them. If not, the RTC folder and EXE have been renamed 'The Trail'. Simply access the folder and double-click the exe to start, then select Part 1 to begin.
If you get really stuck, there is a 100% playthrough on YouTube, here... Youtube.com