The paper says: How the deciphering works: Now my best explanation of the joke is Here is the paper together with the plaintext:

The ages are: In order to see this, EDIT: The above implicitly assumes that all ages are non-zero. If we drop this assumption, we get some more solutions (Although I do not think this is intended):

11: _ _ _ _ _ _ _ _ - _ _ _ _ s ‡ {Ra, D, GM, G, MO, f, R, BG, h, JZ} BONUS: _ _ _ _ _ - _ _ _ _ _ _ _ _ s {D, C, SS, BT, AC, P, RC, DS, HV, M, PU}

I think to the answer to the riddle (which I found just to late, but credits to xhienne) is: Bonus picture of the riddle:

The new naming convention is the following:

The beginning The first puzzles The third blanket Crosses This suggest the following rule: Irregular grids The flower/star/explosion/fireworks-symbol The last blanket The last puzzle Using ...

The completed grid: Step by step solution: As a first step,

I can ensure that I receive at least To get this amount of coins, I could apply the following strategy: My friend can also ensure that I do not get more coins than this in the following way: So it ...

I think the passcode might be Building on the answer of zekei:

His favourite fruit is a The numbers are

The next number is: We can namely do the following:

The puzzle types are: The solved grids: The categories: My final answer:

The final grid: An explanation of the path I took: (Thanks to Beastly Gerbil and Deusovi for helping with eliminating the brute forcing!) As a next step, we observe Next, Let's look at the top ...

Partial Answer Alphabet grid This gives However, we can do the following: Large grid with instructions I found only one way of doing this (but this was before the top row was added): Stars, 4's ...

Joseph probably likes

The completed grid: Step-by-step solution: We start by looking at the We finally filled in a digit, just 80 more to go! Lets look at the bottom box now, Next we look at row 5 again. Now we can ...

The answer is: The solved puzzle is: (I believe that the solution is not completely unique, but at those points I made the choices that seemed most reasonable.) Now we can read of the following ...

I think you might be As others have pointed out,

Completed grid Step by Step Solution Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10 Step 11 Step 12 Step 13

The completed grid Step by step solution Step 1 Step 2 Step 3 Step 4 Step 5 And this completes the puzzle!

The completed grid: Step-by-step solution:

I believe the answer is: This works as follows:

I found another one: 11:

The three twisty things are: These can be found in the pattern from David Starkeys answer as follows: These things are indeed twisty, as

Partial answer, using the findings of Gareth McCaughan As Gareth McCaughan already expected, These values completely agree with the values found by Gareth McCaughan. However, there is still a ...

The completed grid: Step-by-step solution: Now comes the first deduction which is a bit trickier: Next, we look at Now we are almost done!

The answer is Reasoning for even $n$: Reasoning for odd $n$: