On the differences between Shadowdark and Swords & Wizardry
If you find yourself comparing all kinds of different OSR systems for your next campaign, this might be helpful for your considerations. Many of these differences also apply to BX and its variants, I am just more familiar with S&W.
- Shadowdark has unified resolution mechanic (d20 vs DC) versus S&W’s mix of mechanics (Saving Throw, d6 rolls, d100 rolls, etc)
- Shadowdark uses a roll-to-cast magic system versus Vancian (traditional D&D) casting in S&W
- Shadowdark uses a gear slot system whereas S&W tracks weight
- Shadowdark uses individual initiative versus side initiative in S&W
- Shadowdark uses 5e modifiers versus OD&D attribute modifiers
- Shadowdark goes up to level 10, S&W up to 21+
- Shadowdark provides no rules for hirelings, mass combat and bastions vs full rules for this in S&W
- Shadowdark has death after d4+CON rounds, S&W at 0 or at minus level
- Shadowdark’s Fighter is very different from S&W’s Fighter
- Shadowdark uses a talent roll at advancement
- Shadowdark rest recovers full health (or d4 with variant option), whereas S&W heals 1HP in two or one days
- Shadowdark has XP for treasure only, S&W awards XP for kills and treasure. Thus statblocks for monsters in Shadowdark do not contain XP. XP rates for advancement also differ.
Looking at this with an open mind, the biggest difference is really only roll to cast, the Fighter, XP and unified resolution mechanics. The rest is really in the realm of house rules. Aside from these mechanical considerations, both systems provide free pdf versions of their rules, however, S&W is much more generous in this regard: Shadowdark provides the base four classes in slimmed down quick start rules. S&W provides the full books for both Core and Complete in older editions. So if providing full rules access to your players is a concern, both games have you covered, but S&W provides the complete package including some print on demand options.