Balancing combat for a solo player?

[Katasi]

So I can only get one player IRL, but we both prefer combat heavy adventures. What cr's comparible to level should be looked at? For example, could a 4th level character run though an adventure made for a 1st level 4 character party? Or would 4th level have far to easy of a time at it?

[Pan151]

Depends on the nature of the encounters and the class of the player. If a lv1 encounter consists mainly of a single big "boss" then a lv4 character would probably stomp it to the ground. If it consists of multiple minions, then they're probably gonna get stomped due to the action economy. Of course, a lv4 spellcaster would almost certainly stomp any standard lv1 encounter with their spells.

In short you're gonna have to "eyeball" some changes here and there to make sure that both the CRs and the action economy are where they should be for 1 character. As far as CRs go,you are probably good, though that again depends on what class the player is. A lv4 fighter would be moderately chalenged soloing a lv1 campaign, while a wizard should probably be able to easily handle anything just a CR or two lower than their ECL.

[Katasi]

Depends on the nature of the encounters and the class of the player. If a lv1 encounter consists mainly of a single big "boss" then a lv4 character would probably stomp it to the ground. If it consists of multiple minions, then they're probably gonna get stomped due to the action economy. Of course, a lv4 spellcaster would almost certainly stomp any standard lv1 encounter with their spells.

In short you're gonna have to "eyeball" some changes here and there to make sure that both the CRs and the action economy are where they should be for 1 character. As far as CRs go,you are probably good, though that again depends on what class the player is. A lv4 fighter would be moderately chalenged soloing a lv1 campaign, while a wizard should probably be able to easily handle anything just a CR or two lower than their ECL.

I'm considering running the player through A Dark and Stormy Night, and they'll either be playing a fighter or sorcerer. The highest CR in there is 2, but almost all of the combats are in very tight confines, which means a spellcaster would be right in toe to toe with the primarily melee beasties

[Uncle Pine]

Helpful link. (http://www.d20srd.org/extras/d20encountercalculator/)
I think a 3rd-4th level adventurer could reasonably run through a 1st level adventurer. However, the amount of efforts required to do so entirely depends on whether the enemies can break the action economy or not. A 1 (CR 1) vs 1 (ECL 4) encounter would end in a single round (and would probably be boring), but a 4 (CR 1/4) vs 1 (ECL 4) encounter will be way more exciting even though the final encounter level (EL 1) is the same.
To sum up, in my opinion a solo adventure is similar to a "reversed adventure" where the PC acts like a wandering boss that has to face many weaker opponents (just like a red dragon would face multiple PCs). Thus, he should often be outnumbered, unless you want him to cut through the enemy lines without even sweat. I don't know the "A Dark and Stormy Night" module, but tight spaces are nice (especially if paired with multiple enemies).