Would you think this result is entertaining or annoying?

[The Cats]

I'm a new DM working with a group of brand-new players. It's going very well so far. The campaign is pretty railroady to be honest but I don't think they've noticed (any decision they make just tends to point towards the same result, but I think I've kept it subtle enough.) and they're enjoying it regardless.

I wanted to run an idea I had for an adventure I've come up with by you. This is supposed to be something fun and lighthearted as a break after a spooky horror ghosty haunty thing. Keep in mind these are brand new players who have never done tabletop RPG or even really been into fantasy anything before but are absolutely loving it.

A green dragon has put a geas on the party in exchange for letting them explore a dungeon it controls to look for the macguffin. After exploring the dungeon they must go to the green dragon's rival's lair and steal a powerful object for the green dragon.

The rival is a copper dragon and his lair turns out to be a beautiful magnificent mansion that acts as a 'hotel' for creatures from lots of different locations and planes. An old man greets them and tells them the master will be out for awhile but feel free to make themselves at home as long as they don't disturb the other guests. In conversation the old man also drops hints that the master keeps it's hoard in the north tower (or wherever).

Upon infiltrating the north tower, the group is met with a number of rooms full of puzzles, riddles and challenges they must pass before coming to the final room where they find the powerful object along with a number of other powerful magic items.

Now here's the part that might be entertaining or might be annoying: All the objects are mimics. After a round or two of hopeless combat the old man appears and transforms: Turns out he's been the copper dragon the whole time! He gets rid of the mimics, congratulates the party for being so entertaining and making it t the last room and rewards them with a lesser magic item. Upon finding out why they were trying to steal from his lair he laughs at the foolishness of letting a green dragon put a geas on you and uses his far more formidable power (The green dragon is adult, the copper is ancient) to break the geas.

Your opinions? If you feel that it would be annoying can you suggest a better way to handle it? Knowing the group I feel like they would enjoy it but if it only sounds entertaining to me and you all think it's annoying then I'll concede my opinion is likely wrong and I should change it.

[Demidos]

It sounds...okay.

I mean, it definitely could be real fun, but I would be a little careful about promising them a giant hoard of stuff and then ending up giving them...a wand of cure light wounds. You know? It just feels anticlimactic. I feel like there should be something more rewarding at the end of a long adventure, especially when it feels like a super-powerful NPC just stepped in to "nope, you didn't find a hoard".

A couple ideas:

Would it be possible for them to instead get a chance to play against the copper dragon in some sort of game, since that is both in character for the dragon and (maybe) fun for the party? The more they win the more items they get.

Perhaps offer them permanent free lodging at the hotel. Maybe they even get to keep the tower for themselves, as the traps had been placed by "a previous dragon running the hotel" and the dragon had never had the time to go through and clear them out. Pretty meaningless mechanically in the great scheme of things, but friendship with a dragon and a permanent base are things alot of players appreciate.

Perhaps they all get the chance to fill their pockets with as much gold as they can carry, as the dragon was very entertained watching them get past his traps, and pays them for the great amusement. This plays into having them encounter very odd and silly traps, such as tanks of acid breathing sharks, buckets of paint that don't deal damage, boxes of toads from which they must kiss the right one based on a riddle else the others grow to medium size and attack, or other such shenanigans.

Just some thoughts. In short, if they put alot of effort into getting into the room, it seems a bit harsh to take away their reward without at least a consolation prize.

[The Cats]

snip

Just some thoughts. In short, if they put alot of effort into getting into the room, it seems a bit harsh to take away their reward without at least a consolation prize.

I do plan to give them a something nice. They've each given me a list of a few magic items they'd like their characters to have so I'd be handing out something from the list to each of them.

I like the idea of giving them the tower as a base. I'd have to think of a way to make it limiting though since having unlimited access to a magnificent mansion at their level seems a little too powerful. Maybe they're given an item that will set up a door to the tower but once set it cannot be moved, so they have a cool, magic tower for a base but they can't take it with them wherever they go. Yet.

I love your trap ideas as well. The copper dragon is going to be a silly prankster character so they fit beautifully.

[Avalander]

You know your players better than I do, but... I would be pretty annoyed. Basically you're forcing them to take a terrible choice that will end up in them making a fool of themselves.

First of all, willingly accept a geas from an evil dragon is an awful choice (willingly accepting a geas from anybody is a pretty terrible choice, truth to be told). And then, the copper dragon is basically making fun of them from the moment they set foot in his lair. They face (I assume) lethal traps to get to a joke room mislead by the dragon itself to be rewarded with some magic toy because they provided the dragon with a good laugh.

After this, the next time some NPC more powerful than my character tried to set me on any course of action, I would probably just go to the beach or something to avoid embarrassing myself again.

Here you are a couple of suggestions:

The PCs could go raid the dungeon for whatever reason and after they've raid it, the green dragon appears claiming that the dungeon belongs to him. The PCs are pretty screwed now, so the dragon can offer them a deal: steal that magic item from the copper dragon and bring it to him and he won't kill them. Moreover, they get to keep the loot they collected so far from his dungeon. It's still quite railroading, but it feels better to do something you know is foolish if it's to save your life. You could add the gear spell to the deal, but if you don't and the PCs choose to break the deal you've got an awesome story arc with the dragon sending minions after the PCs and stuff, so why bother?

And then, you could have the copper dragon asking them to help with a real problem (perhaps some kobolds got into an area of his lair and he has more important things to do, so he asks the PCs to clear it for him or something) instead of using them for his personal amusement.

[The Cats]

snip

And then, you could have the copper dragon asking them to help with a real problem (perhaps some kobolds got into an area of his lair and he has more important things to do, so he asks the PCs to clear it for him or something) instead of using them for his personal amusement.

The traps aren't at all lethal. It's like a contest the dragon set up that guests of the hotel who have the balls to try can go for. When they complete the challenges he greets them as champions kind of thing. Doesn't start laughing until he finds out they're working for the green dragon (who has always been a joke to him). But yes, I can see how the whole situation could be frustrating. I feel like my players would be ok with it but I'll have to think it over some more. It's a few sessions away in any case.

The green dragon showing up after the dungeon is explored is a good idea. The idea of a green dragon's revenge hanging over the party is nice too: it might even take him awhile to find them. Let them go on other adventures and then (maybe when they're actually strong enough to take on a dragon) BAM "Hey remember that powerful creature you all screwed over awhile back?"

[Vitruviansquid]

This would be annoying to me for the following reasons:

1. Everything seems like it would break down if the PCs would just say, "no, we don't want your stupid Geas."

2. Geas is dumb and bad. The less it is used, especially against PCs, the better.

3. The room-where-everything-is-mimics is training your players to not trust you and play hyper-paranoid. This will become annoying to you in the long run, as players refuse to advance the plot or dungeon because they are too busy checking everything a thousand ways for tricks.

4. The entire plot of this session makes the players out to be pawns of far greater forces that are really just kinda screwing around with them in a way that doesn't matter to anyone significant in the end. I would feel kind of condescended to at the end of this session.

[The Cats]

This would be annoying to me for the following reasons:
snip

Thanks. I will rework the plot of this adventure to make it seem less "pawn of fatey."

I like Avalander's idea of introducing the green dragon without using geas.

Perhaps the heroes must make their way through the tower to win an audience with the copper dragon? Or if they decide to go theft instead of diplomacy, the final room actually is the dragon's hoard, with the dragon sleeping on top of it. Maybe they'll want to explain the situation. Maybe they'll just succeed in stealing the item and filling their pockets with gold. I'll have to decide what item would be powerful enough for a green dragon to desire it without causing a mid-low level campaign to get completely kerfuffled in case they don't want to actually bring it to greeny.

EDIT: Ooh! The copper dragon is holding a challenge and anyone who makes it through the tower gets to pick something from his horde. He won't let the green dragon compete because of their ancient rivalry so the green dragon sends the party to compete on his behalf. They might go for the item the green dragon wanted when presented with their prize options or they might just grab whatever the heck they want.
The copper dragon will discourage them from picking the thing the green dragon wants, bribing them with more magic items and gold to dissuade them.