So i made this program "SimCity47" And i want to Distribute it with my friends, but since i and my friends are in a coding school, the will probably start cheating with it and chaging the vars and lists, so anyone knows a good way to protect lists?

Thnx in advance  

I don't think there is a way with TI-BASIC, sorry.

Isnt there also a way to like copy the list, reverse the order and save it to like example "LCS47B" and then when u run the program, it unreverses it and checks if the 2 lists are the same?

Hmmmmm, well i would sure think of that it just i never worked with encryption

How about a simple checksum? For example, append -Sum(list) to the end, then when loading you can check whether the sum is zero (or with some tolerance, if necessary)

There is basically no protection against knowledgeable TI-BASIC programmers. However, if you think they will be too lazy to check the source code, you could use some kind of checksum method. For example, if the list is always 25 elements of the data, the 26th element could work as the checksum:
0→L1(26
sum(L1
Ans-247iPart(Ans/247→L1(26
Then to see if the data has been tampered with:
L1(26→A
sum(L1)-A
If A≠(Ans-247iPart(Ans/247
Return

However, that won't prevent a user from incrementing one list element and then decrementing the next. For that, you could do something more complicated like squaring each element, adding 1, then multiplying all of the elements together, modulo 247 and use that to check if the data has been tampered with.

If someone can see the source encryption of any kind is no use

You do need to consider if the number of elements being change will cause any dim errors. You could make a second list that holds the sum and a 1 or 0. You could then  get the sum of the variables list check it to the othe r list and if  the send element is 0 ignore results if 1 exit the program. If you lock the program then you could force a divide by zero error to frustrate their lazy effort to even change the list in the first place, they will tet a divide error and can't even enter the source to remove it.

How about this :
1. Set up list
{1,2,3,4->L1
2. Take the list and turn it into a matrix:
For(I,1,4,1
  L1(I)->[A](I,1
end
3. Rotate the numbers around a bit
For(I,1,4,1
  rowSwap([A]
end
4. Store back to list
Matr►list([A],L1
5. Delete Vars
Delvar[A]DelvarL1DelvarI
6.
7. PROFIT.