How different is it coding for nspire versus coding in the TI-83/84?
Because if somebody made a health bar in TI-83/84, it seems to me like they could port it over to the nspire without too much difficulty, unless the two languages are really different...

Oh, erm, I had written a post which asked what a health bar is, but when I looked over it, it felt slightly insulting, so I deleted it.

On that note, what exactly do you mean by a health bar?  You mean like a health bar in a RPG with fighting characters and stuff, or something else?

For the avi to gif, try this website:
http://media-convert.com/
It does its conversion all online, so it should be free.

The interface is a little messy, but if you poke around the menus, you should be able to find an option to convert avi to gif.

I can't vouch for it's reliability in video conversion, but I've used it to convert other file types fairly successfully.

Edit:
Also, you could try this one:
http://www.zamzar.com/index.php
(same thing as before, only the interface is more cleaner)
End Edit

(The trick is to search for file conversion in general, not just avi to gif)

As for Circle, I wonder if the trick actually works under OS 2.53/2.54MP?

Yup.  Works on OS 2.53 MP.

Do you think scrolling will slow the grayscale down?

Nah, probably not.  Or, at least, it won't be too noticeable.  It might be slower when a blank bubble is expanding (but only because there are so many more squares to check).
The way I'm envisioning it, integrating scrolling should only add about 5-10 lines max, as long as they're carefully crafted and written.

Right now, my greatest concern is getting the timer and the getKeys to work together nicely. 
I seem to have an irrational phobia of interrupts - it's probably because my calculator keeps getting RAM clears almost every time I try experimenting with them...

~~~~

Questions:
Is an 18x18 maximum field fine?  I think that if I use appvars instead of L1 to store my map data, I could increase the size dramatically at the cost of taking up RAM.  (A 40x40 field would take up about 3200 bytes, for example.)
When compiled, the program is 7873 bytes.  Is this a reasonable size?

Ahh, that would be why. 
Well, thankfully, this isn't much of a problem.

btw, can you have more then one custom interrupt running at a time?

The following works:

.TEST
ClrDraw
0->A->B->C
fnINT(TIM,6)
While 1
    If getKey(4)
        1+C->C
        Text(0,0,C->DEC)
    End
    If getKey(15)
        Goto END
    End
    If A>=118
        0->A
        1+B->B
        Text(0,10,B->DEC)
    End
End

Lbl TIM
    1+A->A
Return

Lbl END
    FnOff
    LnReg
    ClrDraw

It acts as a timer while allowing me to increment the variable C at whim,
but if I try doing this:

.TEST
ClrDraw
0->A->B->C
fnINT(TIM,6)
While 1
    getKey->D
    If D=4
        1+C->C
        Text(0,0,C->DEC)
    End
    If D=15
        Goto END
    End

...etc.

the getkey doesn't appear to work, or store anything to the variable D.

Meh?  What gives?

(I added indents for clarity)

Aah I see, so it was definitively the DispGraph making such a difference. Now you know how slow the TI-82/83/84/+/SE LCD drivers are .

As for the Undo, maybe add difficulty modes or bonuses for when someone wants to disable it. Another option to disable showing the location of mines when you lose and a bonus for it seems like another cool idea.

I don't really like the idea of using bonuses to reward the player if they chose to disable the Undo button.  If the player avoids clicking the undo button, there's really no difference between the player who leaves it enabled and the one who disables it.

I think that instead of rewarding the player, I should penalize the player for clicking the undo button - in exchange for having unlimited shots at solving a particular minefield, they can't save their time to the high scores list.

Besides, I can't really think of any kind of bonus I could give.

But I think I will add an option to toggle to show the location of the mines when you lose.