Boulder Dash C64 cave - mid-level gameplay with diamonds and boulders
Boulder Dash C64 mid-level cave. Source: Lemon64.

Fan Community

Boulder Dash Fan Forum
boulder-dash.nl/forum
The active Boulder Dash fan community forum - custom cave packs, BoulderCaves+ engine discussion, and construction resources. The community that kept the franchise alive during First Star's dormant years.
Lemon64 - Boulder Dash
lemon64.com/game/boulder-dash
C64 game database entry for Boulder Dash - box art, screenshots, reviews, and user ratings. The source for the C64 gameplay screenshots used on this site.
Lemon64 - Boulder Dash II
lemon64.com/game/boulder-dash-2
Lemon64 entry for Boulder Dash II: Rockford's Revenge - screenshots, ratings, and downloads for the 1985 sequel.
Lemon64 - Boulder Dash III
lemon64.com/game/boulder-dash-3
Lemon64 entry for Boulder Dash III (1986), the Epyx-published third entry in the series.
Lemon64 entry for Boulder Dash Construction Kit - screenshots and user reviews of the 1986 level editor.

SID Music and HVSC

HVSC - Boulder Dash SID
hvsc.c64.org
HVSC path: /GAMES/A-F/Boulder_Dash.sid and /GAMES/A-F/Boulder_Dash_II.sid. Peter Liepa's original SID compositions confirmed via STIL.txt composer attribution. All SID files on the Music page are sourced from HVSC.
HVSC - Peter Liepa
hvsc.c64.org - Liepa_Peter
HVSC directory for Peter Liepa - Boulder Dash III and Construction Kit SID files at MUSICIANS/L/Liepa_Peter/.
DeepSID Player
deepsid.chordian.net
Browser-based SID player with ReSID accuracy. Use for the most faithful playback of Liepa's compositions. Search for "Boulder_Dash" in the HVSC file browser.

Game Databases

MobyGames - Boulder Dash
mobygames.com
Comprehensive database entry covering all Boulder Dash platform releases, credits, and box art. Primary source for multi-platform release information.
Wikipedia - Boulder Dash
en.wikipedia.org
Wikipedia article covering the game's history, development, mechanics, and franchise. Primary reference for factual claims across this site.
Wikipedia - Peter Liepa
en.wikipedia.org
Wikipedia entry for Peter Liepa - programmer and composer of the C64 Boulder Dash titles.
Wikipedia - First Star Software
en.wikipedia.org
Wikipedia article on First Star Software - the publisher behind the core Boulder Dash franchise.

Speedrunning and Construction Kit

speedrun.com - Boulder Dash
speedrun.com/boulder_dash
Speedrun leaderboards for Boulder Dash. Records for the original C64 version remain active. Speedrunning Boulder Dash reveals optimized cave-completion routes that are completely different from how casual players approach the game.
Steam - Boulder Dash 30th
store.steampowered.com
Boulder Dash 30th Anniversary on Steam (BBG Entertainment, 2014). Includes classic cave recreations alongside new content. The modern way to play Boulder Dash on PC legally.
Archive.org - Peter Liepa Interview
archive.org
Archived audio of Peter Liepa's ANTIC podcast interview. Primary source for many factual claims and direct quotes used on this site.
Zzap!64 Archive - Issue 1
archive.org/details/zzap64_magazine_01
Zzap!64 Issue 1 (May 1985) at Archive.org - the issue containing the Gold Medal Boulder Dash review. Full magazine scan available for free reading.
Select a track on the Music page
DeepSID