That Time I Got Reincarnated as a Slime: Lord of Tempest

That Time I Got Reincarnated as a Slime: Lord of Tempest 「転生したらスライムだった件 ～魔国連邦創世記～, Tensei Shitara Slime Datta Ken ~Makoku Renpou Souseiki~」 is a 2D turn-based role-playing and city-building game on iOS and Android. It generally follows the story of the actual series while the characters used to fight in battle are obtained using a gacha system.

Currently this is the only available game of the series and has no announced English patch as of yet.

Battle Mechanics
Lord of Tempest follows an automatic turn-based battle system where the attacks are based on some sort of speed value*. The battles are broken into 'waves' of enemies, with each wave having 1 to 5 enemies to fight against. Similarly, the player can also bring up to 5 characters per battle.

As each character deals damage, a red bar* fills up which allows the player to unleash the character's respective special move. If the player so wishes, this can also be switched to be in automatic mode, however, in this case, the characters will use the special skill as soon as it is ready rather than waiting for a proper time.

The battles can also be toggled to speed up to twice the normal game speed in case of boredom or personal choice.

Home Base
Immediately after leaving the Sealed Cave, the player is released onto the pre-establishment of Tempest i.e. the Goblin Village. There the chibi sprites of various characters from the series roam about. Here, the player can build and upgrade building eventually leading to the growth and creation of the Monster Country Tempest.

Gacha
Characters from the series are obtained using Magic Steel, the premium currency of the game, and range from 1-star rarity to 6-star rarity. If a rarer variant of the same character is obtained, the less rare character is erased, or is automatically converted into EXP for the rarer character.*

Trivia

 * Phrases/words marked with an asterisk (*) require more digging into.