*Gold Ore and Emerald Ore is now somewhat more aplenty underground and new ores (Sapphire and Ruby) are also introduced
*However, caves are more dangerous now, loaded with carved stone blocks that are instant-kill crushing hazards, spikes that instantly kill you if you fall on them and highly reactive powderboxes
*Lots of new blocks and items from decorative use, tools/utilities and new types of weapons with interesting mechanics (including a couple of Spelunky Classic exclusive items)
*Three new structures: mini-mineshafts, vaults and golden idol traps
*Dynamic environment music (music plays randomly if you're underground)
*A new death mechanic that punishes you if you are careless, you now respawn with a no-healing debuff and decreased health/hunger temporarily (config-togglable)
*Fall damage now stuns entities briefly, including you so be more careful about high drops now! (config-togglable)
*Dynamic light, this is also not just client-side so it actually updates lighting-levels (config-togglable)
+0.2: boomerang, altar tile-entity, arrow traps (unimplemented/partially working, saving for 0.2 or later), corpses, lantern, kapala, journal, new mobs (snake, bat, cobra, spinner spider, caveman, giant spider, damsel, shopkeeper)
Q: What is Spelunky?
A: Spelunky is a vertical roguelike by Derek Yu, with inspiration from treasure-hunting cliches and Indiana Jones. It features permadeath, random level
generation, high difficulty and an emphasis on mastering mechanics, emergent gameplay and making decisions on the spot based on level-gen and unpredictable but predictable enemy AI. Spelunky currently has a sequel in development, slated for release next year.
Q: Can I include this in a modpack or look at the source for code-referencing?
A: Sure! Just give credit where due, especially for modpacks
Q: Is this server-compatible?
A: It is, from my basic LAN testing. I may need to do throughout server-testing with an actual jar, later, though.
Q: I ran into a bug/crash/etc!
A: Go to this link and submit an issue! Thanks! (issue tracker)
A: Do not use the issue tracker, please contact me via twitter/etc or join the Discord Server and use the relevant #ideas channel
Some more besides the new sapphire/ruby ores:
Decorative block, semi-common underground. Currently has no purpose, just for world-decor to make caves slightly more lively.
Found semi-common randomly generated underground. When broken, they will drop a random crate item such as a Bomb Bag, Ropes or rare items like Spring Shoes. However, you are more likely to receive bombs or ropes than something valuable like Spectacles.
Found rarely from crates or craftable for compacting reasons. It can be uncrafted into four Bomb Bags, which can be further uncrafted into bombs or right-click used to get bombs in inventory.
Box of Flares
Semi-uncommonly found underground and emits light. Drops three flares when mined. Destroyed if placed in water or falls into water. Flares are throwable objects, emit light in hand (if config-enabled) and can be thrown to produce a flare block. Handy when you need to light up a spot across a massive gap, huh?
Semi-commonly found underground. Breaks instantly and drops a few gems (sometimes large, more usually small ones) along with an empty chest projectile-item. Vaults have a variant that instead drops 8 random large gems (emeralds, sapphires, rubies, diamonds). Non-vault chests have a 0.5% chance of spawning a live bomb on you upon opening.
Found underground semi-rarely in Golden Idol structures...which are booby-trapped. They slow you down temporarily upon pickup (config-togglable) and can be crafted into 10 gold ingots.
Nearly indestructible hazard but can be destroyed by explosions. They can walked on from the same level but falling onto them will instantly kill you.
Carved stone block affected by gravity. If it falls on you, it's an instant kill!
Randomly generated traps, stuffed full of highly reactive gunpowder. They are more dangerous than TNT as they explode instantly upon being hit by the player or ranged-ammo and will also explode if they fall and land.
Various kinds of treasure. Ruby/sapphire are primarily dropped by their ores but you can also find small gems and sometimes large gems from pots, chests, etc.
Obtainable from crates. Max stack of eight and gives eight ropes when consumed. Ropes can be used to throw and launch rope, which are climbable semi-solid blocks affected by gravity.
Bombs and Bomb Bags
Bombs are obtained from crates. Throwable item, explodes when it hits a block/player/entity. Also has sticky/bouncy variants, craftable using bombs with respectively Bomb Paste/Slime Balls.
Bomb Bags are obtained from crates or made via compacting three bombs. Primarily acts as a storage/source of bombs as they can both be right-click used to give three bombs or putting three bombs in a crafting grid will produce a Bomb Bag to compact them.
Dropped from crates, rarely spiders or more commonly cave/mineshaft spiders. Can be used with bombs to craft sticky bombs and each bomb paste can be used 64 times before being depleted completely.
Non-usable item that auto-activates if you fall +3 blocks. It will be consumed on use and automatically set your fall-height to 0 before landing, preventing any fall damage on activation.
Obtained from crates. Has durability halfway between stone/iron and twice the mining speed of gold pickaxes. When they break, they drop an reusable throwing item called Mattock Heads. They can also be used as a weapon.
Craftable from sapphire, ruby or emerald. Not shown but you can also craft hoes. Emerald, sapphire and ruby respectively have the harvesting-level of stone, iron and diamond however their speed and durability is generally equivalent to being better than their vanilla equivalents.
Off-hand slot gloves that adjust the aim of projectiles like rocks and skulls to be straight.
Gloves that allow you to climb. When equipped in off-hand, stand against a +2 block high surface and hold right-click to climb.
Equipable boots-slot item that provides a Jump Boost effect when equipped.
Rare special glasses that give you permanent Night Vision when equipped.
Equipable chest-slot item that completely negates fall damage when equipped. Basically a permanent equipable version of the Parachute item.
Jetpack's are awesome! Right? When equipped in chest, jumping will make you levitate semi-quickly, allowing you to hover at a quickly ascending pace or reach places out of reach for you.
A standard weapon. Medium-high durability, easily craftable (two leather and a stick) and does 2.5 hearts of damage each strike.
Melee weapon. Does five hearts of damage and can cut through webs with ease.
A much weaker version of the Shotgun. Does decent damage and ammo is much easier to craft, cost wise.
Rare and very powerful gun. Ammo is somewhat costly but each shot does 10 hearts of damage at max.
A gun that fires cobwebs. Spawns climbable cobwebs on hit and entity-hit stuns enemies.
A gun that fires blasts of ice. Projectiles spawn ice and stun enemies for a period.