Excellent game! So far really enjoying it! Note: Once you finish 81, you may need to restart the game in order for the challenge mode ones to load. They were showing blank for me once I finished the main game, but were back on refresh.
As others have said, locking helps. Also, there is no need to *guess*, even on the 8x8 modes. You can slowly piece it together with logic. Start with rows where you can confirm or eliminate numbers easily. e.g. if a row needs 30, but with ALL numbers active, is at 35, then you know that any number greater than 5 MUST be in the answer. You can lock those as confirmed. You can also lock any number where it would be impossible to get the answer if there are no other numbers that could pair with it. e.g. in the above example, if there is a 4, but no 1's, then the 4 MUST be in the answer as it would be impossible to remove the 4 without breaking it.
I beat it, but I found the last level (19) to be quite buggy. The red levers would cease functioning/rotating, and the trolleys would get stuck once the elastic was broken. Made getting the square to the correct place much more difficult than it had to be once the puzzle was essentially solved.
Nice quick and easy game. A bit buggy where the correct solution would fail because a block or two of a colour would separate from the group and become inaccessible. Same solution would work the next try because blocks would not run away.
I thoroughly enjoyed the first game, and the second is even better! Fun, challenging (but not insanely so) and the music and sound effects really add to the game a lot. Even the "undo" button sound adds a surprisingly good tone addition to the main BGM at times. Well done!
Hard badge done, finally. If anyone wants a tip to grind it out, ignore everything except darts for left/right and lasers for eyes. Once you get spike arms it's more or less smooth sailing. Now let us never speak of this again.
I wish units wouldn't waddle away from a castle before waddling towards it in order to capture it. If they're fighting AT the castle, once it's at 0 they should just enter right away.
It's an alright game. Gotta echo the comments by a couple top posters -- the handling is BAD! Slaloms are exceedingly frustrating. And the forced camera shake is really bad for those of us with motion sickness. If it was limited to bumping it wouldn't be so bad, but why am I being jarred around constantly on a straightaway??
Monsters' Den was the very first game I played on Kongregate and ultimately what got me hooked on the site. It is great to see another version of this classic come out! And from what I can see, this one will continue a great tradition!
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 "Rullo"){kind=icon}
 "String Theory 2"){kind=icon}
 "The Space Game"){kind=icon}
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 "Bullet Heaven 2"){kind=icon}
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 "Strand"){kind=icon}
 "Bloons Super Monkey 2"){kind=icon}
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Thanks Gallicus!!