“We were cautious about doing a yearlong narrative,” Dave Kosak, Lead Designer on the Hearthstone Missions team tells me. “From the beginning we wanted to make sure that each individual set had a strong enough theme. Even if you weren't paying attention to the whole year, they were still fun and exciting on their own. But if you were following, then you would have the satisfaction of seeing a story unfolding in three parts.”
Tombs of Terror is the latest Hearthstone Solo Adventure, arriving as part of the
Saviors of Uldum expansion. Continuing the story laid out in Rise of Shadows and the Dalaran Heist, we now follow the League of Explorers – a team of heroes – in their attempt to stop the Plague Lords under the control of the League of E.V.I.L.
“A lot of the story was planned in advance, because we had to plot out the whole year,” Dave continues. “For a couple of years now we've wanted to tell this story about all the Hearthstone villains teaming up. Part of that plotting was aligning all the class identities. We had five villainous characters in the League of E.V.I.L. and then our four heroes from the League of Explorers. And it was like ‘Hey, that adds up to nine’. Interestingly, we were well into designing the year before we realised that we should probably come up with a good ending for this.”
“From the beginning we wanted to make sure that each individual set had a strong enough theme. Even if you weren't paying attention to the whole year, they were still fun and exciting on their own.”
Of course, the grand finale is coming with the next expansion. In discussing the dramatic middle chapter that plays out in Tombs of Terror, Blizzard weren’t quite ready to open that mysterious card pack quite yet.
Following in the footsteps, framework, or structure that we’ve seen in Solo Adventures before – in Tombs of Terror players take on increasingly more challenging foes before going card to card against a big boss. A Plague Lord. That said, Tomb of Terror still feels different, challenging, and unlike anything that has come before in the Hearthstone single-player space.
“Our players have become attached to these iconic characters in the Hearthstone universe and creating this deep experience where you can progress and see them get stronger and explore with them in different ways was one of our goals,” Stephen Chang, Game Designer on the Hearthstone Final Design team adds.
“And we wanted you to feel like you were making these heroes more and more powerful with the time you've invested,” Dave explains. “Signature Treasures that get more powerful as you go, and then with the Plague Lords themselves - instead of being a really difficult final boss that is binary where you win or lose - anyone can feel like they made progress because their health is saved and carries over.”
“You have more oxygen available to you to sort of scale up and get stronger,” Stephen continues. “For Heroic in particular, we were given a challenge by the mission teams to make them as difficult as possible. So, we made them as hard as for ourselves as possible.”
Large-scale battles where progress is saved – a first for Hearthstone. Where players slowly chip away at a huge health pool or do the impossible and take down a Plague Lord in one go. Which, when broken down this way takes on the air of a roguelike. A style of RPG or action-game where progression in the form of growing in power and repetition go hand in hand. Where getting sent back to the starting line is all part of the adventure. Think
Dead Cells, Rogue Legacy, or the recently released
Children of Morta. Tombs of Terror, by choosing which hero to take into battle, and letting them develop over time – has elements of a roguelike in much the same way Kobolds and Catacombs introduced the well-known concept of exploring an RPG-like dungeon within Hearthstone.
“Our players have become attached to these iconic characters in the Hearthstone universe and creating this deep experience where you can progress and see them get stronger and explore with them in different ways was one of our goals.”
“We talk about roguelikes a lot in the office and one of the things that makes them so memorable is they're what I would call ‘spiky’,” Dave responds when the topic of roguelikes is brought up. “And that’s in reference to the power level that sometimes spikes. In Tombs of Terror sometimes you’ll get a bad draw, but maybe you’ll get all the right things and it's amazing. We have one treasure that triggers every time you play an even cost card and another treasurer that triggers every time you play an odd cost card. If you ever have a run where you get both of those, it's crazy. And that's a spike. It’s not a nice, even, and predictable gameplay trajectory. These spikes are part of what make a roguelike compelling.”

“Also, roguelikes are generally very difficult games,” Dave adds. “And with Tombs of Terror that's intentional. That makes it replayable because then you look forward to those spikes. Every spike is a story. Every kind of crazy thing that happens is a great story. That's something we talk about a lot, that element of randomness.”
With anything found in Hearthstone there’s usually a reason for it to be the way that it is. Often this comes down to the theme of an expansion, with new cards, mechanics, and powers amplifying a certain perspective. For a yearlong story, or any Solo Adventure, it comes down to character and story. This then draws on established lore not only within the larger Warcraft universe, but Hearthstone as well.
“Going back to the first dungeon run that we did in Kobolds and Catacombs, we talked about having some meta progression,” Dave continues. “Some ways you could unlock more hero powers. Ultimately, we scaled that back because we were trying to launch the game on time. So that idea carried forward and we've always wanted to explore it. And I think we really explored it, no pun intended, here with Tombs of Terror. We really wanted to tell the story of the four explorers, our four heroes in this chapter of the story. And so that level of progression made perfect sense.”
Building on the theme of an expansion, the story being told, and the lead players – these being the League of Explorers – this allows the team a little bit more freedom when designing without the need to balance for competitive play.
“Roguelikes are generally very difficult games, and with Tombs of Terror that's intentional. That makes it replayable.”
“We allow players to do much more powerful things, but we still want to keep it all within the realm of Hearthstone,” Stephen explains. “Where no matter what the interactions are, they still feel like they belong in Hearthstone. Still draw from the same realm of possibility. But, ramped up and super exciting because some of the things you could do in a Solo Adventure should also feel a little bit taboo.”
“We can certainly explore a design space that we wouldn't explore in the collectible set,” Dave confirms. “Especially when it comes to cards that do mean things to the other player. Like Reno’s Lasso which literally steals cards out of your opponent’s hand and puts them into your own. I can't imagine that in Ranked play. That would be extremely frustrating to play against, but a super fun in a Solo Adventure.”

The allure of focusing on power, cards that swing the balance of power in a decisive manner, is always there. “For us, a lot of it is the cleverness of it,” Dave explains. “If a card is just straight up powerful, then it's not interesting. It's not an interesting decision to put it in your deck because obviously you would. It's not interesting to play it because obviously you’ll play it. What's interesting are cards that have an effect that if you combine them with other cards in interesting ways, you get a lot of craziness. That's what we aim for. One of our values is to make the player feel smart and Solo Adventures are a great opportunity for that because you can combine cards in really interesting ways.”
The Hearthstone Solo Adventure, as we see it today began with Dungeon Run in Kobolds and Catacombs. A framework that has informed each subsequent Adventure, with new directions explored and lessons learned as the team grew more confident in their ideas, execution, and understanding of what works and what doesn’t.
“That core gameplay of the Dungeon Run or what we sometimes call build-as-you-go, that is a fun way to play Hearthstone,” Dave recalls. “Right from the very beginning it felt like there were going to be a lot of different variations that we could play around with. Over time we've taken this core idea to different extremes and played around with different things. In the Witchwood expansion, we learned that with the hero powers being so powerful – ultimately, it could be viewed as really limiting.”
"If a card is just straight up powerful, then it's not interesting. It's not an interesting decision to put it in your deck because obviously you would. It's not interesting to play it because obviously you’ll play it."
“With Rumble Run, we were aiming for super-powered combat, having these two gigantic champions clashing. Again, the power level was so high there the games felt very swingy and players reacted negatively to that. We've sort of learned a lot of lessons along the way that we've incorporated into subsequent adventures and now here in Tombs of Terror.”
“There's plenty of more space to explore within this build-as-you-go format,” Dave concludes. “And we're going to keep playing around with it and we'll keep playing around with other formats as well. Taking a break and doing something different like we did with Puzzle Labs. I think there's just so much possibility in single player Hearthstone.”