It’s a procedurally generated real-time platform digging game, which displays obvious influences from the likes of Dig Dug, Repton and Mr. Driller, as well as in no small part Spelunky. I’ve described it in the past as ‘Spelunky methadone’ – short of buying a PSVita (unlikely) it’s the only way I can achieve that kind of roguelike hit while out of the house. (It’s also better suited to mobile play as session times are shorter and the interface only needs one finger.)
While Doug Dug initially feels like a quite shallow (and in some ways unfairly random) game, there are quite a lot of subtle design features that only make themselves apparent with extended play.
Doug Dug has two stated objectives: collect as much treasure as possible to gain a high score, and dig as deeply as possible (triggering the brilliant message “You have achieved a new low”) without dying. There’s no time limit or forced scrolling so the player is free to plan their moves (most of the time) without having to perform digital gymnastics.
Once the player learns the basic rules of how the game works, they can stop playing reactively, and start thinking about how to use the environment to achieve their immediate goals. Below I’ve listed some of the rules I’ve observed to give you a head start.
The treasure that Doug the dwarf seeks is encountered in several states.
Treasure that can be mined out of blocks is always visible and is instantly collected when a block is mined out by Doug. It takes the form of precious gold, so-so silver or shameful bronze ore (worth $300, $200 and $100 respectively) as well as coloured gems that become more valuable (up to $5,000 in my experience) the deeper one goes. If a block is destroyed by falling the treasure is destroyed with it. The easiest and stupidest way to die in Doug Dug is to tunnel horizontally through a cliff to reach a distant treasure, resulting in a cave-in.
Treasure dropped by killed enemies falls until it comes to rest on a flat surface. While this treasure only comes in gold/silver/bronze varieties, later enemies can drop many pieces. Loose treasure has some interesting properties: dragon’s fire and lava particles are extinguished when they come into contact with it (so for instance, a dragon surrounded by loose nuggets is effectively harmless) and likewise rocks falling onto it are instantly destroyed. Unlike in Spelunky, loose treasure falling on enemies doesn’t hurt them.
Background treasure is fixed into the back wall, and moves in slight parallax with the foreground scene. It’s collected instantly on contact. It’s worth noting that treasure (and items) within two spaces above Doug can be collected by swiping upwards, so sometimes it’s possible to use air control to pluck background treasure even when there’s no platform nearby.
Finally there are treasure chests, which can contain a random amount of treasure or which will spawn a random item (never the same as the one being carried by the player) or a lit bomb when opened.
A key thing to know if you’re chasing a high score is that the game has a combo system: if three or more pieces of treasure are collected within about a second of each other, a Treasure Trove bonus of $1,000 x the number of pieces of treasure is awarded. This can often be exploited through careful route planning and ‘pre-weakening’ treasure-bearing blocks.
Collectible items that bestow temporary or permanent effects can sometimes be found in chests and crates, or just lying around in the world. Doug has a single inventory slot that can be used to store items for later activation. The last three items on the list are only found in crates and have a state purchase cost to access.
Gold Rush: Doug can dig faster for a limited time. Useful for out-running enemies or just to relieve the tedium of clearing a particularly dense expanse of rock.
Feather Fall: Doug can fall any distance without injury. Can be used mid-fall. In a game where lots of cheap deaths are caused by leaps of faith and collapsing floors, it’s at least some solace.
Support: Makes a single block sized ‘roof’ that Doug can stand within to be safe from collapsing rocks. It can also be dropped on enemies.
Hard Hat: Essentially an extra life. Protects Doug from one instance of something that would kill him. Doesn’t use an inventory slot. Useless against deep lava.
Jackhammer: Gold Rush on steroids. Doug is briefly invincible and constantly digs downward, although he can be steered to destroy blocks and enemies to his sides. Particularly useful for dealing with massive amounts of lava and trolls.
Invincibility: Doug becomes impervious to all hazards (including burning and crushing) for a few seconds. Also seems to speed up digging.
Rats: The weakest enemy, rats can move left or right and burrow through blocks in front of them. The can be killed by running into them or falling on them. Very often they commit suicide by digging out the support for blocks above them.
Bats: As in Spelunky, these are treacherous little swine. Bats fly in any direction until they hit a wall, and then turn 90 degrees. Doug can despatch them by ‘digging’ at them in any direction, but there are annoying edge cases where a bat will clip the player’s hitbox off-centre and still kill them. As the game only tracks a few tiles above the top of the screen before garbage collecting, bats that fly off the top of the screen seldom return.
Dragons: Added in an update, dragons move similarly to rats, however they can randomly decide to stop walking and spew a stream of fire particles. (Their eyes flash momentarily to warn of this.) At close range their fire can destroy blocks and chests (and other enemies). While on the same level they can usually be easily dealt with, they can be extremely dangerous if Doug gets trapped downhill to one.
Mummies: Mummies are two squares tall and can be dealt with on open ground in the same way as rats and dragons. However, they’re not affected by walls and falling rocks: if a mummy doesn’t have enough room to stand on a platform, it will transform into a ghost and start slowly zig-zagging up the screen until it finds enough space to rematerialise. The strategy for dealing with them then becomes clearing enough space for them to spawn and chase Doug.
Trolls: As far as I know, the ultimate foe in the game. Trolls are massive and can simply push through walls of rock. They kill Doug on contact. If you don’t have a jackhammer or invincibility, it’s probably curtains, although fortuitously triggering TNT, bombs, lava and falling rocks – or just nimbly running away – can sometimes work. (Edit: Evidently you can kill trolls using your standard attack, but the conditions to allow this aren’t entirely clear. Possibly you need to have the hard hat item.)
As with treasure, there’s a combo system for making multiple kills – this only counts for kills Doug makes directly.
Lava: Fluid is simulated in the game as a collection of loosely jiggling particles which each have a heat/energy value (denoted by colour). Lava contained in a tight space will stay ‘hot’, whereas if its container is broken, it will slowly tumble downhill until it finds another container or else will slowly disperse. Falling rocks extinguish lava, so you can build stepping stones or bridges by engineering rockfalls above lava fields.
Dirt: The softest material that Doug can dig through is also the most dangerous. Dirt has very few ‘health points’, and can be weakened by too much weight, or sometimes just spontaneously, resulting in massive chain reaction collapses. When digging through dirt it’s usually worth waiting and observing if surrounding pieces are cracking, and to ensure there’s a clear escape route.
Falling: Doug can sometimes ‘surf’ on falling rocks, repeatedly landing on them as he falls, which cushions otherwise fatal long falls.