Yo, JSA, I have some ideas!
1. Put in some small blocks, which are easier to push. They can be used later in the game as small letters, not capitals. Also, put in the word "weak" so that when he uses it, Jim can only push the small blocks instead of the big ones.
2. Adjust the heaviness of the block depending on the difficulty of the word's pronounciation. Something like "Force" can be a bit heavier than "Push." Make so that it also applies to syllables too.
Hey! Word Suggestion: Find, To "find" this word, there is some sort of maze (in a big room) Letters F I N and D will be randomly placed somewhere, You gotta find the end though, There might be some traps including other letters (Example: V H A E) If you combine these, you will not go forward, Hope this is good! :D