DLC is probably a little difficult, depending on what you want to do. For in-game items you'd probably have to make everything ahead of time, script everything into the game, and then limit the player's access to the items until you have some kind of key (a text file with a serial code that the game would read, and then unlock the items). Add on levels would be pretty easy, you could just export the add-on levels as .dat files, and then update the main .exe file to recognize the level and load it.
Neither of these options are very secure, because one could simply give the key file, or level to someone else if they figured out how it works. You'd have to blindly trust your users, because Game Editor doesn't have any drm capabilities. Drm is not very popular anyways, nobody likes screwing around with it. Just look at what happened earlier this year with the whole Sims ordeal.
Regarding DLC as a design concept:
There's positive and negative aspects to it (as there is with everything).
This is based purely on speculation, as well as my own as my own purchasing behavior. I do not have field experience in this area I'm afraid.
People are probably more willing to download a full game with optional dlc than to download a limited demo. With that, you have a much fuller experience than a demo, but not as full as a full game.
Less piracy overall (I assume... I for one find piracy extremely distasteful. I haven't studied the statistics). In a mobile market, people are much less likely to pay 99 cents for a game with so much free stuff out there (seems ridiculous)
But...
If the DLC isn't enticing enough, or not very useful, most will just ignore it. One would also have to be very careful to keep the game play balanced. If players who bought weapons are
infinitely more powerful, the game will seem unfair. It's acceptable if there is some advantage though.
Here's the “ideal loop” of a freemium game (Taken from
gamedev.tutsplus.com- The player downloads and installs the game.
- He begins to play with free items.
- He’ll be able to kill some enemies or complete some objectives – but it’s a bit hard, he loses more than wins. He’ll repeat this step until either he becomes an addict or he uninstalls the game.
- He’ll see another players using amazing items and playing better because of them; here he’ll notice the Shop area of the game.
- He’ll spend some time scrolling through all the items he could get and imagining playing with them. (This is why it’s important for the items to be desirable.)
- He’ll buy the items he wants and head back to the game.
- He’ll repeat the above steps until the game shuts down, he gets bored, or something forces him to change his habits.
Looking at this list, we can see a few important points such a game needs to fulfil:
- You need to create free items and a free gameplay that the player really likes.
- You need to create amazing paid items that feel like they’re worth actual money, without them offering such a big advantage that they’d unbalance the gameplay.
- You need to set great prices and have a lot of premium items to have a better chance of enticing your player to buy something.