Instant Dungeon! is 15% off from May 11 - 14 to celebrate its newly added features; Steam Trading Cards and Steam Achievements.

Steam Achievements:

There are 51 achievements, you can view them from the Steam client or by selecting "Achievements" from the options or pause menu in-game.

You can see the achievements here:
http://steamcommunity.com/stats/326720/achievements

Steam Trading Cards:

You can now grab 5 trading cards each is an original composition by the artist Lukasz Jastrzebski. There are also 5 profile backgrounds and 5 emoticons which you will be able to collect randomly by crafting badges.