(Psi)SeveredHead
Adventurer
*I know, the problem arises when the DM and the player have different views on what constitues what type of act, but that is part of the social contract, not an alignment problem...could happen in any scenario of the game..."What do you mean I can't swim upstream all day...DnD doesn't have fatigue rules"
Maybe it's because of the example, but:
1) I saw that exact example (except the water wasn't running, it was an ocean) in 2e. There were rules for that, although probably not in a "fatigue" section.
2) In 3d, there were rules for getting fatigued. There's no specific rules for swimming upstream, but if you can get tired from running for a minute (start making Con checks), getting tired after swimming upstream should happen even faster.
3) In 4e, it'd be a skill challenge to see how far you can go, with failures resulting in lost healing surges (plenty of skill challenges allow for that; Dark Sun is full of them), or (to copy 3.x) the victim would be slowed and weakened for some time until they stop and then maybe make an Endurance check.
4) There are numerous situations where a DM can tell a player their PC "can't do something". Players are generally more satisfied with a physical restriction (eg "you get tired", "you need a Strength DC of 50 to knock down that magically enhanced adamantine door" than something mental like "you're too scared of him; he made a high Intimidate check." - they'd usually be satisfied with taking penalties, which could but won't necessarily prompt them to act scared.)
