Snarf Zagyg
Notorious Liquefactionist
I'm aware of the hack and slash might hate it but I've asked them if they where interested and did warn them it was combat light and more thinking. They told me they where for it I think having something little different can be interesting and me adding some more combat for those that do want it should help.
To be honest, I would NOT put in more combat. It's not like TOH is an entire adventure path, so it's not going to be more than a few days (or, in 1e terms, a few minutes .... SHOULD HAVE CHOSEN THE OTHER TUNNEL!).
The entire point of the module is that it is different. That it is all puzzles and traps. @Stormonu addressed this, and I will concur; if you want to up the difficulty, then make the puzzles and traps more "save or die" type. Adding more combats would take away from the experience. IMO.
If you are looking for tips, try purchasing the original pdf version and compare!
S1 Tomb of Horrors (1e) - Wizards of the Coast | AD&D 1st Ed. | Dungeon Masters Guild
S1 Tomb of Horrors (1e) - In the far reaches of the world, under a lost and lonely hill, lies the sinister Tomb of Horrors. This labyrinthine cryp
www.dmsguild.com
Man, I LOVE those old illustrations.