Exploration is silly within the current frame of D&D and its magic largely makes challenges and obstacles meaningless...
unless one homebrews and/or steals the journey/travel rules from other fantasy RPGs.
- Food and Water (D&D should have conditions rather than just hit point loss. There is no sense in why thirst should affect a low-level fighter more so than a high-level fighter)
- Equipment deterioration (imagine having to dealing with a torn waterskin, a damaged shield, a broken holy symbol...etc)
- Clothing deterioration (a damaged boot might hinder someone's movement - trying hiking with one, dishevelled or torn clothing may offer hindrances within the social pillar. Why do we not have these conditions?
- Weather (i.e. sunburnt skin, heat irritation, biting cold extremities etc). I mean just because you made the save doesn't mean you shouldn't be suffering consequence or a condition. D&D is extremely simplistic with you make the save = no damage taken. There is no nuance.
Item Saves. D&D games generally do not include item saves for area affects or attacks. Fragile items are never affected. People should fear the devastation caused by a
Fireball or
Ice Storm.
Binary Skills. Skills are far too binary with their success and failure conditions. The DMG with its
Degrees of Success and
Success with Complication (even Failure with Complication) should be utilised to make Exploration (and Social) challenges more interesting.
Fail Forward is great for pushing the story in interesting routes.
The Banes and Boons idea from A5e is a great idea IMO to tack on to D&D.
Skill Challenges. These should be viewed as a possible loose framework for the Exploration and Social Pillars for situations that are not immediate. They are very useful.
Magic OP. Introduce homebrew rules for the cost and risk of magic in the setting.
Perhaps animals can sense the arcane and shy away from it - making hunting or stealth checks more difficult
Perhaps magic leaves a residual aura or light which lasts for a certain period of time depending on the strength of the spell.
Perhaps rituals cost a Hit Dice (residual energy needed)
Being under the effect of too much magic could have the potential of making one infected with magic fever (random wild magic disturbances). I encourage one to use different wild magic tables and not just the one in the PHB.
...etc
Cure All Perfectly Phenomena. Disease, Poison, Wounds and Exhaustion (at higher levels) are overcome quite easily in the std game.
Changes will need to be made if you plan on making any of this interesting. Perhaps Cure Disease/Poison allows one to make an additional saving throw rather than just removing the disease all-together? Perhaps healing hit points does not necessarily remove a Wound?
Ancient Texts. Reading certain ancient texts with
Comprehend Languages might instil temporary madness or incur some other condition such as Can't sleep (cannot long rest), hopelessness (cannot regain Willpower)...etc
Reading ancient tests could release imprisoned creatures, unravel permanent spells, offer insight into past/future...etc
Power of the Word. Perhaps certain forgotten or esoteric languages release words of power (Wild Magic) even while communicating normally. It would make the linguist in the party able to control the Wild Magic better than most.
Mounts & Vehicles. Limitations and vulnerabilities of mounts and vehicles should also be factored into Exploration.
Magical Travel. Teleportation/Planar travel may require Con checks for the discombobulation. (One could use this for
Plane Shift all the way to
Misty Step)
And this is before utilising a suitable encumbrance system, accounting for overland movement, lighting conditions/durations and record the keeping system for arrows/bolts ...etc
I've realised the only way to satisfy myself with much of the above detail is to partly record these details myself as I officiate the game. I do much of the record keeping on my large tv monitor. My tv monitor is plugged into my nuc (computer) box and everyone can see it. I realise not everyone has access or wishes to bother with it, but this is how my table have dealt with it (mostly for my peace of mind).