[PC] [2000–2008] Top-down pixel-art game with a boy in a red cap using a hammer, forest hub, colored keys and skeletons

I'm looking for a PC game I played around 2008, but I'm almost sure the game itself was older. It came from a CD compilation of arcade games, so it may have been a shareware or indie title. Here is everything I remember: Platform: PC (Windows) Graphics: 2D pixel art Camera: Top-down with a slight angle, similar to early Pokémon games or Zelda: Oracle of Seasons/Ages. Main character: A young boy wearing a red cap. Weapon: A gray hammer with a brown handle. When attacking, I think he raised the hammer above his head. He could attack in all four directions. Health: Displayed as hearts. Movement: Grid-based (the grid wasn't visible). The game started in a forest hub with several paths. Each path led to a different area. You had to complete an area, then return to the forest hub before entering another one. Inside the levels: Each level took place on a single screen. Colored keys (blue, red, green, yellow) used to open matching colored doors. Enemies included skeletons, spiders, and other fantasy monsters. At the end of the first set of areas there was a boss, which I remember being either a giant skeleton or a giant spider. The art style was colorful and very similar to Game Boy Color Zelda games. It is NOT Hammerwatch, God of Thunder, Power Pete, Mystic Towers, or any Zelda game. Does anyone remember a game like this? Even obscure shareware or Game Maker games are welcome.