(A version of this review originally appeared as a blog post of mine during IFComp 2015. Paradise was withdrawn from IFComp because it had been released prior to the comp. It has since gone offline, so my review is here as a record of what it was like.)
Paradise is a text-based online world/system for any number of players/users in which anyone can create, walk around in and inject simple programming into textual objects. The objects aren't modelled to be anything in particular, but typical uses for them include making locations and putting choices and objects into those locations. Interaction is via a mixture of parser-like typing and clicking on hotlinked words.
In my first session in Paradise, I created Cafe De Los Muertos, placed it in a location recommended by the implementors and put something inside it.
As an open-ended project which began four years ago, and one which may not contain any goal-oriented adventures that are easy to find, Paradise was likely to have scored poorly in IFComp. However I think that whether you like parser IF or clicky IF, or both, Paradise might appeal to you as a creative tool. There's nothing to stop you building a game or experience in Paradise and then linking others to it. Another big plus is that neither creators nor players (and technically, the two aren't distinguished from each other) require accounts or passwords to log in or to protect their creations. You can just visit the website and start doing stuff.
Text objects in Paradise are called vessels and operate on a concept of enclosure. Such basic concepts are explained in tutorial vessels you'll encounter soon after logging in. Basically, every vessel is inside another vessel. So you could make a location (one vessel) by typing 'create grassy meadow', then put an object inside it (a vessel in a vessel) by typing 'enter grassy meadow' then 'create chest'. If the object has compartments, they could be vessels in the object vessel. But there are no actual programming rules about the nature of vessels. You could stick a whole new world inside an object if you like – after all, it's just another vessel. You can also pick up editable vessels and put them elsewhere, or embody them, the latter being the means by which you create an avatar. You wouldn't want to be driving a default object like the teapot forever.
The most basic kind of programming lets you attach any useable Paradise command to a vessel through a 'use' link, which can also be activated by typing 'use such-and-such'. You can then repaint the word 'use' as something else – read, press, etc. – whatever word you want the player to type to use (enter) the vessel. You can nut this stuff out by following tutorial topics which consist of locations and dialogue, not boring old instruction files, or by just typing 'help'. More advanced programming is available, but it would be possible to put together an adventurous structure or CYOA adventure with the basics alone.
I suppose what's annoying about the interface is the fact that you can't get away from having to keep switching between clicking links and typing things. Or clicking a link and then having to hit return to execute it. My other gripe is that allowed punctuation in creator content is quite limited. No apostrophes take, no capital letters take in some circumstances, no exclamation marks take (actually, maybe that last one is a plus), etc. For the more literate-leaning, these things might bug.
I'm personally interested in exploring more focused material than what I saw here thus far, but I don't even know how big the place is or what's already in there. I could easily have missed a lot of stuff.