Both are excellent games that are worth your consideration. I cannot stress that enough. I do favor one game over the other but that is not because I feel that the other game is somehow inferior. It's just a matter of preferences. I do think that here on ENWorld, you are going to get a lot more people pointing you in the direction of Shadowdark.
But let's be clear. They are different types of games, albeit with some overlap. Shadowdark is OSR (with more modern design) without just being a retro-clone of a previous edition of D&D. In contrast, Dragonbane is "Neo-Trad, and here I use "Neo-Trad" in its original sense, as coined by Tomas Härenstam of Free League Publishing:
I would say that Mutant: Year Zero is...a game very much in the „neotrad“ part of the spectrum – it’s got the production values, ease of use and plentiful campaign material of a traditional RPG, combined with the kind of clever and thematic rules design usually found in the indie games.
While he is talking about Mutant: Year Zero, the basis of Free League's Year Zero Engine, I would say that this also applies to Dragonbane. But Dragonbane isn't OSR in the sense that it's nostalgic for old school D&D. Instead, Dragonbane is like an updated version of Sweden's own
Drakar och Demoner, which evolved out of Basic Roleplay in Sweden. So it's Neo-Trad but also with a different subject of old school nostalgia.
Shadowdark
Core Vibe: gritty dungeon crawling, lethal combat, survival emphasis
Mechanics
- D&D family of games
- d20 roll high against GM's DC system with D&D's six attributes
- Simple class and level progression with randomized class progression
- Dungeon Procedurals: real time torches, always on initiative, darkness matters, etc.
- OSR Ethos: rules over rules, OSR principles, etc.
- Magic: roll to cast with chance of mishaps
Dragonbane
Core Vibe: "mirth and mayhem" so it's a bit more pulpy and lighthearted "beer and pretzels" game (IMHO!)
Mechanics
- Basic Roleplay family of games but simplified
- d20 roll-under skill system
- skill-based, not class/level-based
- Push mechanic: fail a roll, you can retry but with consequences
- Monsters (but not all enemies) always hit and the GM rolls what they do.
- Magic: have spell prepared, roll to cast, spend Willpower point cost, also with chance of mishaps
- Ducks. Duck people are a thing. Some people love it. Some hate it.
Official Support: Shadowdark has the core rulebook, and it finished its highly successful Western Reaches Kickstarter earlier this year, which expands the game with a lot of new material. Kelsey Dionne is also pumping out a lot of new content through her Cursed Scroll zine, some of which has been incorporated into the Western Reaches Kickstarter. You can get some Shadowdark material for free. I believe that the Quickstart rules give you a pretty solid chunk of the game for free.
Dragonbane is published by Free League, which comes with their usual high production quality. Dragonbane has an absolutely killer box set that comes with the full rules of the game!, solo rules and solo adventure, a complete sandbox adventure, dice, cardboard standees, battle mats, cards (treasure, initiative, improvised weapons), a map, pre-gen characters, and blank character sheets. Free League has also published a Bestiary and an adventure path (Path of Glory) for Dragonbane. They had a Kickstarter this year for a city campaign (City of Arkand) and a new magic book (The Book of Magic), which we should be getting the beta preview files for "soon."
3rd Party Support: You will be able to find a lot of 3rd party products and fan materials for both games. So if that is you concern, then don't worry about it. There are a lot of adventures and modules out there for both games.
There are more Shadowdark materials than Dragonbane, but Shadowdark is hot stuff in the OSR community, particularly as a gateway OSR product or for people who primarily play(ed) D&D. Shadowdark is more English-language accessible.
Dragonbane (Drakar och Demoner) was basically Sweden's "native D&D" game, so a lot of the support comes initially out of the Nordic area. That doesn't mean that there is no English fan support. It's just that a lot of the enthusiasm and products are also primarily coming out of Sweden.*
* From what I recall, when Free League announced that they had the rights to Drakar och Demoner (Dragons & Demons), they were actually surprised that there was any desire from English-speakers for the game in English, and then they were suprised by the popularity the game had from the English-speaking sphere for a Swedish game.
I have an ongoing Dragonbane game that I am playing with my partner, using the box set. They have enjoyed it. It's one of the handful of TTRPGs that my partner has expressed interest in playing again. Part of the reason has to do with the things like the standees, cards, and such as well as the roll under system so they never have to look to me about success. We will probably have another game session this weekend.
I do think that part of the appeal of Dragonbane
for me is that it exists
outside of D&D's usual wheelhouse of classes, spells, monsters, divine and arcane magic, etc. So as a filthy American who comes from the D&D side of the game with no prior experience with
Drakar och Demoner, Dragonbane feels fresher and more unique. That's just me. But that will be the exact reason why other people will love Shadowdark; it's another variety of D&D.