These hacks basically mod the games to have newer and harder levels. C-Lolo 1 has 50 new levels as does C-Lolo 2, though the 2nd game also has new Pro maps making it 54 new levels in all.
Here are 2 screenshots from C-Lolo 2.
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To get both hacks, please follow the links below.
Challenging Lolo 1: http://www.zophar.net/hacks/files/Lolohack.zip
Challenging Lolo 2: http://www.zophar.net/wwwthreads/attachment.php?Cat=&Board=romhack&Post=293066
Apply the IPS patches to Adventures of Lolo 1 (US) and Adventures of Lolo 2 (US).
Personally, I think the first one is harder than my newer one, but both games will challenge you.
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Enjoy.