As you play the game, it will switch between day and night. The gameplay differs between the two phases.
Day Phase Edit
During the Day Phase, you match tiles of different types to collect resources, heal yourself and replenish your magic. The character above the screen will use the resources you gather to upgrade buildings, which upgrade the tiles, causing them to count towards more resources during the day. Each time you perform a move, the sun will move along in the sky. After 20 moves, the sun will set and the Night Phase will begin. You can use magic to cast spells which can reshuffle the board, make the character move faster, skip the day or stop the movement of the sun.
During the Day Phase, the tiles consist of food, minerals, wood, clay, paper and shards. At the beginning the game, you will only have food, mineral and wood tiles. Shortly after, you will build the Brick Maker's Hut and the Weaver's Hut, which add the tiles for clay and cloth respectively. Once you have collected enough shards from chests during the night section, you will build the shrine, adding the shard tiles. Progress on the shrine is shown by the completeness of the floating orb located to the right of the Sawmill.
You must match the tiles in straight-line groups of 3 or more. When you match mineral, wood, clay or paper tiles, they become resources in your storehouse. Once you gather a certain number of a resource, it becomes a block of said resource, which can then be used to upgrade buildings. When you match food tiles, your health is replenished a little. When you match shard tiles, it replenishes your magic. Your health slowly depletes every time you successfully move tiles (at a rate of 1/10 of a heart per move).
The resource tiles can be upgraded by upgrading their respective building. Upgrading the Brick Maker's Hut upgrades clay, upgrading the Weaver's Hut upgrades cloth, upgrading the Forge upgrades minerals and upgrading the Sawmill upgrades wood. When a resource tile is upgraded, it supplies more resources to the Storehouse. As the game progresses, the storehouse will be upgraded, which also upgrades the food tiles. Shard tiles cannot be upgraded (however the buildings image file shows 5 entries for the shrine?).
You can focus on upgrading one building by selecting it once the upgrade bars are shown. This will put a spinning star above the building and will put priority to the construction of this building. Only one building can be given priority at a time and selecting the current priority building will clear its status.
Choose carefully when upgrading buildings as these also affect the tiles in the Night Phase. See below.
Night Phase Edit
During the Night Phase, you match tiles of different types to arm yourself and spawn monsters to fight. The character above the screen will use the sword (or his fists) and shield to battle the monsters you spawn. Each time the character defeats a monster they will gain XP and the moon will move along in the sky. Sometimes the monsters will drop chests with items that can be used. Once you defeat (20?) monsters the night ends and you return to the Day Phase.
Later in the game, after defeating a Lich and collecting the dragon summoning spell reward, you can battle a dragon during the Night Phase. Once the dragon is defeated the game ends, giving you the option of continuing or New Game+ which resets your building upgrades but leaves the shrine unlocked. (possibly more?)
Each time the dragon is defeated and New Game+ is selected, an internal prestige counter is incremented. The difficulty of the game (of the dragon at least) increases as prestige increases.
During the Night Phase the tiles consist of sword, shield, ranged enemy, beast, and humanoid icons. These are the opposite sides of the tiles from the Day Phase so as you upgrade Day Phase tiles, Night Phase tiles also upgrade.
Clay = Beasts
Food = Humanoids
Minerals = Swords
Cloth = Ranged Enemies
Wood = Shields
Shard = Lich
Beware when upgrading the Brick Maker's Hut and Weaver's Hut as they only have 4 upgrades, compared to the 8 of the Forge and Sawmill and thus greatly increase the difficulty of the night phase. Level 4 and 5 ranged enemies can quickly burn through shields and health while fighting melee enemies.