Java Edition pre-Classic rd-131655
Unknown date before May 13, 2009
Client not archived
rd-131655 is a pre-Classic version officially known as Cave game tech test  or Cave Game tech demo was made on May 13, 2009, at 16:55 UTC. This version was never released, but was recorded by Notch from around 17:00 UTC and uploaded at 17:36. It is the first known version of Minecraft, or what was then known as Cave Game, to have been recorded.
Development of this version started around May 10 or May 11 and continued up to May 12, 2009. Features were added that would be later seen in the Cave game tech test video released on May 13, 2009.
- Not listed internally as a block at this time.
- Made with the same graphics from Notch's game RubyDung.
- Made with the same graphics from RubyDung.
- Grass generation is randomized, but it will only generate on fully lit tiles. The higher the Y level is, the more chance there will be of grass generating. At the top of the map, grass will generate on all fully lit tiles.
- Currently has no visible model.
- Has a height of 1.7 blocks.
- Take about 1⁄10 of a second to generate each.
- The size of each chunk was 16x16 blocks.
- Chunks are 16×16 blocks instead of 8×8 because 8×8 chunks decreased performance.
- Chunks are loaded in order of their proximity to the player.
- Make a 256×64×256 tile map.
- The game takes 20 seconds to generate a 256×64×256 map.
- It was possible to fall out of the world.
- Falling off the edge of the world will not kill the player.
- Reached down until a few blocks before the last layer of cobblestone, making a ravine.
- The lighting engine in Classic and Pre-Classic was simple, with only two light levels, bright and dark. "Sunlight" is emitted by the top edge of the map and hits any block that is under it, regardless of distance. It passes through transparent blocks to light blocks underneath. Blocks that do not receive light are in a dim shadow that remains at the same level of brightness no matter how far they are from a light source. Blocks which are darkened also have a layer of thick, black fog applied to them, appearing darker when looked at from further distances.  This caused weird visual glitches.
- Creative mode
- This was an extremely basic version of it. The player could not fly or place/remove blocks and there was no inventory or hotbar to get them from.
- Note: All videos from Nizzotch, Notch's YouTube channel, have been region-locked in all countries.
- "lwjgl IRC logs" (archived) – Echelog, May 13, 2009 (UTC+2).
- Rotab's IRC logs on Archive.org; #minecraft.20090525.log. May 25, 2009 (UTC+2)
- "Cave game tech test"– (Archive) Nizzotch on YouTube, May 13, 2009
- "Cave Game tech demo!" – The Word of Notch, May 13, 2009
- IRC logs: "[18:55:45] <Notch_> the chunk size is 16x16 now.." [...] "[18:56:47] <Notch_> 8x8 chunks are SLOWER"
- IRC logs: "[19:00:52] <Notch_> hmm, I wonder if I could make a vid of this" [...] "[19:14:02] <Notch_> haha, the video ended up at 1.05 GB" [...] "[19:15:36] <Notch_> well, this is annoying. I guess I have to recapture. Google has a limit of 2 gb" [...] "[19:36:42] <Notch_> upload complete, processing video" [...] "[19:50:18] <Notch_> ok, the quality is still crap until the processing finishes, but: http://www.youtube.com/watch?v=F9t3FREAZ-k"
- "About the game" (Archive) – Minecraft, June 2009.
- Rotab's IRC Logs "(10:40:09) <@Notch> heh, the game game tech test video is from the 13'th"[...]"(10:40:18) <@Notch> that was after two days of work, so I started the 11'th, probably"
- LWJGL IRC Logs "[13:34:09] <Notch> i was trying to narrow down a performance issue last night."
- LWJGL IRC Logs "[13:37:42] <Notch> rebuilding a chunk of these takes almost 100 ms, but that's everything, including tesselation, calculating lighting, and building the display list."
- LWJGL IRC Logs "[13:37:08] <Notch> I've got chunks of blocks, 16x16x16 blocks. Each block can have a maximum of three quads, but that's worst case scenario"
- IRC logs: "[19:51:48] <Notch_> i'll update tiles chunks the player first, and force a full update upon game start"
- IRC logs: "[20:02:58] <Notch_> it takes like 20 seconds to grow a 256*256*64 map, though. :-\"