I went into the Preproduction of the Tooltips a bit in the Preproduction Article on this project. A link to that can be found there. Overall, I knew I wanted a floating tooltip. I originally programmed it to be dynamic and move with the mouse (which you can still flip the setting and it will) but the fluidity of moving with the mouse didn't really feel right for something that's supposed to look wooden and rigid. So there's only one spot where the tooltip will appear. I like this pattern because the player will always know where to look for information on what they're mousing over.
The bulk of my time working on the tooltips was spent on these stat icons. I wanted something super graphic that could be taken into other parts of the game and you would know what it is. I started with Viking Runes roughly translated into the made up stats I chose. Then I made an icon but I didn't like how some of the icons were really strong (like the strength icon and pierce icon) but other icons were weak at a small size (attack speed and agility). I tried a bunch of different versions and ended up making little rune stones in Substance Designer so be used in their place.
These are renders of my Stat Icons from Substance Designer. Some of the icons lost their detail at a small size but I felt like they held up pretty decently as a graphic icon that can be used anywhere else in the game. I didn't add color to these because I wasn't sure which way to go. I was originally thinking they could all be the same color (like in my mockups) but ended up making them different colors to further differentiate them. This way I can rely on the UI light to tint them a consistent color and I could just focus on what they actually are. Red for strength, Green for agility, etc.
Although I'm confident that my programming can get the job done, I'm not a programmer so there are probably better ways to implement everything here. Here's a high-level overview of how these tooltips work and some notes I made on the implementation.