It was pretty much straight forward, but time consuming. The only real issues I had were with multiplayer stuff.

The main crazy thing was creating player entity on client with
player = ent_create();
When that player's entity was ent_removed() on the server, the player pointer was not set to NULL on the client. It usually wouldn't matter much because the client wouldn't usually have it's player entity removed, but how this code was set it up, after the player died his entity would be removed, he would go back to selection menu, and then he could select from the 3 available characters again.

Other than that, you get to know what needs to be changed from C-Script to C-Lite fairly quickly. It just takes time and you will find some commands don't exist anymore or have been changed.

I guess some other things is if you have
var vecTemp[3];
you can't access it with
vecTemp.x, vecTemp.y, vecTemp.z
you have to use
vecTemp[0], vecTemp[1], vecTemp[2]

Also,
variables and flags are case-sensitive in C-Lite, so you will be finding yourself changing stuff like my.X to my.x, event_block to EVENT_BLOCK, etc.

And,
many things that used to be bmap, string, etc will now be BMAP*, STRING*, etc.

And,
effects are a bit different, you have to pass (PARTICLE *p) as a parameter, and use p.alpha, etc in the particle effect instead of my.alpha, etc.

Oh yeah, one more thing that was a bit tricky,
your on_enter = function;, on_esc = function;, etc, now need to be placed in the main() function. That was kind of weird.

You well also learn what set() and reset() are pretty quick.

But basically, it is just a time consuming process. I did however convert this in about 5-6 hours with never having used or having any knowledge of C-Lite. I could do it much quicker now. If I was converting a very large program I would go through one thing at a time, like searching the files for define and then changing all the define's to #define's, etc. That would be most efficient. For a smaller program like this though, probably just go through it from top to bottom.

Dang, it was almost 4 years ago when that tutorial was first made. Ahhh, the good old days. I am still bitter about not winning first prize, who were the judges on that contest? (Just kidding, I didn't have all the documentation quite ready by the time limit, but code was done, lucky I got a prize at all. But that documentation was darn good.)

Anyhow, back into obscurity,
Loco