They are similar in that their rules contain the entire game. RPGs don't do that, at least D&D is far from contained in such a manner.
The truth is, RPGs are not anywhere close to being contained by their rules like sports and board games are. They simply are not... it's obvious.
RPGs are absolutely contained by their rules. Why wouldn't they be? What is it you think the rules do?
Some RPG rules are about fairness. Others have nothing to do with fairness. And a lot of the game doesn't have a rule that fits the situation, so the DM needs come up with a ruling/house rule. That last situation doesn't really come up in board games or sports games more than once in two or three blue moons.
That's really inaccurate. The judgment of referees is what you're talking about. Yes, the GM of an RPG performs that function. Would you really say that such a function doesn't exist in other types of games? Sports, in particular?
Really? Let's say the DM and players all get to stack the same bonuses that aren't meant to stack. That's fair. Not the rules, but still fair.
Doesn't that really seem like a case of changing or removing the rule?
Would you allow one participant to benefit from such stacking and not another? No, I don't expect you would. And why not? Because it would be unfair.
That's the only real fairness that there is. Any rules that touch on unfairness are ones that touch the social contract. Like no cheating.
Not really. The Alarm spell isn't as rife with points as the OP would suggest.
"* Does the player's character have an uninterrupted minute of time to cast the spell?"
There will be somewhere close to zero times that this ever is an issue. If there are so many monsters that close to you, you probably aren't stopping for a minute to cast the spell. Outside of there being monsters everywhere around you, there the minute casting time just won't be an issue.
It's chock full of GM Fiat.
Instead of pointing out how unlikely it is... let's look at what happens if that is the case.
I am playing a wizard, and I go to cast the spell as we ready for camp. The DM then tells me that only 12 seconds into casting the spell, a mob of goblins appears on the nearby hilltop. He calls for initiative.
Has he done anything against the rules? Has he done anything unfair? What criteria do we use to determine that?
How do we proceed? If combat erupts around me, is my casting still considered uninterrupted? Can I continue to cast and if I make it for 8 rounds, the spell works? If combat isn't over by then, won't the spell just trigger immediately?
What if I ask the DM about this decision to have goblins show up just after I started casting and he said " I thought it would be a fun scenario for you guys to face one more challenge before camping, and I wanted to see how you'd handle the alarm spell and the risk of losing it, since it was your last spell of that level"? Is the DM breaking any rules? No. Is he being unfair? I don't know... he did it because he thought it would be challenging and fun.
"* Does any potential intruder come within 8 hours, or do they turn up (say) 8 hours and 5 minutes after the spell was cast?"
It takes a rare corner case for this to ever be an issue. DMs aren't going to sit there and just have monsters show up right after the spell ends. And you know what? So what if the DM does. It lasts 8 hours so that the party can long rest and 8 hours and 5 minutes later, the long rest has happened and the encounters hits a fresh party that is awake for it already. This is the second non-issue brought up as a "point where it can happen."
It's not a non-issue. It's a case of the DM clearly acting on knowledge he only has because of his role as DM, and then having NPCs behave accordingly. Perhaps passing it off as coincidence.
Is the DM allowed to have someone show up just after the spell ends? It seems you think yes, based on your "so what" comment. Okay... then who determines how ready the characters are? How much are they able to accomplish before the potential enemy shows up? Are the characters scattered about in a vulnerable formation? Is the ranger tending to the mounts while the fighter's off in the woods relieving himself of all the ale he drank last night, and the cleric is in the middle of praying?
How are these things determined?
By the same guy who decided the enemy showed up right after the spell ended.
"* Does a potential intruder come within the warded area, or open the warded portal? Or do they sneak around the warded portal, or inspect/attack from outside the area?"
This one is more common than the first point above, but still very rare. The overwhelming majority of encounters will enter the warded area, but a few might inspect or attack from outside if they typically are a ranged attacker. Still not an issue, though.
Why is this not an issue?
How is it determined what creature shows up? If the creature can detect or dispel the ward? Or if it's a creature that would typically attack from afar? What about the creature's disposition? Its goals?
These things are all determined by the DM.
"* If the caster (and friends) are asleep, and are woken by this spell, how much can the intruder accomplish while they rouse themselves?"
They get to roll initiative since they are not surprised, which means they get their full round of stuff to do. They may or may not be wearing armor, and they may need to spend half their move to stand up, but they can do anything they would normally do. This is also a non-issue.
Why wouldn't they be surprised? Let's just focus on that. Who determines if a side is surprised in 5e? The DM.
Some folks might say that the Alarm spell should prevent being surprised... but it doesn't say anything about that in the spell. You're making an interpretation here... and it's a perfectly valid one.
But it's also perfectly valid to say that even with the alarm spell going off, the party is surprised, giving the other side a surprise round to act before we go to initiative.
That's a pretty significant judgment call to make that will have a major impact on how things play out. But neither approach is incorrect or unfair... because per the rules, the DM decides who is surprised.
It's GM fiat all over. And that isn't necessarily bad. You're defending it on the grounds that the GM can always be fair. And that seems to work for many gamers. That's cool! But to say it's not GM fiat? Why even argue that? It very clearly is, isn't it?
There's just another way to do it, which is to have clear rules and processes, where all participants are constrained in ways that result in a satisfying play experience.