Grim Clicker

The only way to get a shard chest is buying it for 900 shards, it has nice loot but its better to spend those shards in the +1 SP on level up upgrades.

You get around 15 shards daily from quests&saveicon and 5 for each boss you defeat which does not drop a boss chest, so getting 900 shards will take quite some time.

It is recommended to gather 300 shards, get the first SP on lvl up upgrqde then save 900 shards.
Once you have the 900 shards, save the game, buy the shard chest then reload the save before the purchase of the chest so you can purchase a 2nd +1SP on lvl up upgrade instead.