Controls:

⬆️⬇️⬅️➡️ move
⭕️ [Z] Jump
❎ [X] Skip / continue / Start tutorial (from title screen)

Remake:

The original game for Commodore 64 is "China Miner" by Ian Gray.
(c)1984 Interceptor Software.

How to play

Important: start with the "How to play" tutorial, the first stage is hard!

Miner Wally is the only person to know the location of the Jade Mines belonging to the Pong Dynasty in China. On each of the 30 screens you must collect four objects (pickaxe, candle, lantern and jade vase) before collecting the key to move onto the next stage. As well as the platforms to negotiate you must also avoid the various creatures that populate the mine and if you touch any of them then you lose one of the nine lives, are sent to the start of the screen and all objects reappear. There are various obstacles to avoid or use like lasers, moving platforms and platforms that disintegrate when stepped on. Falling from heights also loses you a life.

As in the original, the game starts immediately hard and in the first stage you quickly have to make a few steps to the left and jump UP to avoid the creature coming straight towards you (and you can't jump up or diagonal due to the lethal stalactites above you).
Press ❎ in the title screen to play the tutorial, read the signs for info.
Here's a short gameplay video that should help you figure out how to beat the first stage and play in general.
For reference and hints on how to beat any stage there's this China Miner Longplay of the original C64 version.

Spoiler: the full play-through of the 30 levels from start to finish in one go (not really the fastest method to finish each stage but the safest).

Differences with original:

• The original game was notoriously difficult and brutal, you started from the first level and had to redo everything after game-over. In this remake you can select the starting stage, so you can train and find the best strategy to finish each level (why not, in the shortest time, see Stats and Achievements);
• You start with 9 lives instead of 5 (you still gain an extra life every 1250 points / 5 stages as the original)
• Some collisions with blocks have been simplified and made less frustrating: for instance you can jump diagonally without hitting the head on platforms higher than 2 blocks from your ground (unless it's the stage ceiling);
• You cannot get stuck jumping up over the stage ceiling as it happened in the original;

Stats page:

⬅️ from title screen.
Aside from the high score, it keeps track of your best performances:

• Longest Run: how many stages you've managed to complete in a single game and the timing of the best run;
• Total Time: (not to be confused with the best run time) this is the sum of all best times recorded for each of the 30 stages;
• Average Time: is simply the above (total time) divided by the 30 stages, see Achievements;
• Take-Away: how many jade vases you managed to carry home; in other words how many stages you've completed in a single game and reaching the exit the cave (finishing 30th stage, e.g. for a takeaway of 5 you might want to start from stage 26);

While in this page press ⬆️⬇️ to select the starting stage (this option is saved).

Achievements page:

➡️ from title screen.
Move ⬆️⬇️ for info on each achievement:

• Hard stages: simply complete stage 1, 5, 12, 21, 28 earning a yellow star each.
• Take-Away: as explained above for the Stats page, reach the exit after completing 3, 5, 7, 10 or 15 of the last stages;
• Average Time: in seconds, to earn the first star you need an average of less than one minute, this should be pretty easy although this row of achievements will likely to be still all greyed-out until you play each of the 30 stages at least once (default time is 15 minutes for an unbeaten stage!); while an average under 40 seconds is more challenging but still doable as you improve your strategy during the training on each stage;
• Longest Run: earn a star for each milestone (3, 5, 10, 20 and 30) of your game progress. These are the toughest stars of course since they need to be achieved in a single game, fifth star
  Upon reaching the "Reset" you still need to move up other 4 steps to enable the "Reset progress" command which is confirmed by pressing the ⭕️ [Z or C] button. This will wipe any saved progress, score, timing and preferences.

Features:

Pixel-perfect collision with the creatures;
P8scii for extra gfx (see post: One-Off GFX);
SFX bank swap (see Music below);
22 animated creatures - 30 stages - How to play tutorial;

Options:

• Flicker (off by default, turn it on only on executable, on webplayer/browser it'll flash inconsistently) 60fps flickering effects for colour blending and transparency; if enabled it'll try to emulate the C64 colour palette, Pico-8 has no cyan and purple;
• Music (slow) you can turn the music off at some point, play it normal speed or slower (like in the original game);
• Particles FX (on) collapsing floor and colliding with baddies;
• Classic Moves / New animation: the Classic mode will animate Wally as in the original, facing you when idle, while activating "New animation" Wally will move more or less like in Manic Miner holding the pose, a little step while jumping, coming down the slides etc.

Music:

The background music "Maple Leaf Rag" composed by Scott Joplin (in the original China Miner by Chris Cox).
The Pico-8 version used in this remake is by @ericb and his player cart is available: Player Piano: Maple Leaf Rag. Fun fact: see my comment there about "China Miner flashbacks"

Credits:

Thanks to:
@thisismypassword for creating Shrinko8;
again to @ericb for the music;
feedback/proofreading: @bikibird, @SmartAlloc, @merwok
Bugs reported: Pico-8 Gamer
you for playing the game!