Some ideas that were pitched but later scratched:

• An outdoor setting as opposed to a cellar.
• Controlling Dzidzia instead of Grunio (as Grunio's almost-all-black fur pattern proved to be a challenge in maintaining both clarity and visual interest in character design).
• A higher color count for player, resulting in shading and a unique left and right-facing player sprites (instead of horizontally flipped)
  
  
• Ability to push single blocks, and to rotate block sets (dropped as it would have made puzzles too easy to solve / too difficult to design.
• Tutorial stages set in house, not cellar. 
• Later half of the game played as the other guinea pig in a scifi environment.
• Water
  
• Lasers
• Quite a large number of cursor variations:
      
• Spinning item sprites (because unclear whether left or right facing)
   
• Mario-style item blocks (dropped because it would have removed ability for player to decide what order to collect items in)
• Enemies, Decaying Blocks, Creature that lays blocks, 
• Squashed-behind-a-block animation for death.
• The following stage: I spent probably more time trying to make this stage playable and fun -and failed- than I'd like to admit.
  
   
  It was eventually replaced with Cavalier Cavidae, a far superior stage in every way.
• A 2-player alternating mode
• Bonus stages with gameplay mechanic like Gruniożerca 1
• Twice as many puzzles

The double-outline item style is achieved by layering sprites and is inspired by dustmop's work on Filthy Kitchen which used the same technique.

From our game:

Grapes from Filthy Kitchen:

For those unaware, NES backgrounds can only display 13 colors at a time (without coding tricks like updating palettes mid-scanline) There is one universal background color and four subpalettes of three additional colors each. When I decided to go with chew toys, as the visual theme for the blocks, I wanted to make the game as colorful as possible.

The chew toys come in four different colors, but only use two subpalettes. This is achieved by using hue ramps within the palettes:

So, black is the universal color and the cool subpalette has a dark violet, medium blue, and light teal while the warm subpalette has a light yellow, medium red-orange, and dark red-violet.

To unify the remainder of the game visually, the quote screens and title screen are all constructed using those same two subpalettes:

Gruniożerca translates to Grunio the Devourer.  Grunio is the name of this actual guinea pig. 

@arhneu The "gru" prefix is a Slavic onomatopoeia for the purring/cooing noise a guinea pig makes. The suffix is there to make it into a pronounceable name. Roughly translated: "The one that purrs". 

Żerca means eater or devourer.  https://en.wiktionary.org/wiki/%C5%BCerca

So, it seems Gruniożerca could be more literally translated as Purry the Devourer!

Three cart-and-box copies of the game were produced by emunes.pl and auctioned off to raise funds for the following fundraiser: https://www.siepomaga.pl/iwo-maciolek.

Print logo created by hand-tracing my pixel logo from a TV screen, scanning, and auto tracing as vector.
Spot illustration was my second attempt at the drawing. The first is a hideous failure, and on this page as well:

A significant amount of work was completed on a spin-off called Gruniożerca 2: Dzidzia's VR Playground with a visual themed inspired by Metal Gear Solid VR Missions.

In the editor, you would take on the role of Grunio designing Holodeck / Danger Room-style simulations for Dzidzia to play. In the games users, players would have controlled Dzidzia, in an attempt to solve the room puzzles.

This possibility is not entirely off-the-charts, but we have removed it from our priorities for the foreseeable future.

"The Great Cavy Rescue!" subtitle was added retroactively after titling the game's sequel.

Although the first Gruniożerca has been ported to many systems by a number of different developers, the internal plan for the Gruniożerca  series (if it continues past what's been produced) is:

• Each numeric sequel follows a different gameplay structure.
  • Gruniożerca  (arcade-style catch-the-falling-objects)
  • Gruniożerca 2 (sidescrolling, block placement puzzle platformer)
  • Gruniożerca 3 (overhead, block destruction puzzle game)
• Main entries starting with 2 would follow "The Great Cavy _______!" naming structure.
• Spin-offs that retain core gameplay component would share the same number (Street Fighter 2-style), but have a different subtitle (such as Gruniożerca 2: Dzidzia's VR Playground)