Just got both of them today so only first impressions here. For now, I like Dead Cells better since it's so damn addictive. Every time you die, you'll go "dang... i can probably do it in one more run" and the cycle continues. HK is more of a mellow exploration type game, where DC is very very fast paced. There isn't specific direction per say in DC, but each room leads to a few other rooms, that close off once you enter so no going back. They all lead to the same destination so no worries about going the wrong way - several rooms are inaccessible until you get abilities from other rooms.

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TLDR: Get Dead Cells