Having played Arcane Worlds since v0.19 I think every new build has brought something new to the table. Progress on the game might not be fast given that there is only one developer but it is certainly steady and v0.25 is almost like a different game to v0.19 now. One of the first major surprises for me was just how much better the randomly generated worlds looked after the generation code was revamped to build the worlds around the gameplay elements rather than the other way around. Before colours were mostly the same and random terrain was sort of thrown together. Now you will find pillars, lakes, valleys, forests and more with proper palettes that all fit together very well in making a believable and natural-looking random world. Couple those elements with terrain effecting spells like Fracture and Volcano you can actually have a lot of fun just terraforming worlds and customising them to your liking.
Spells are no longer found randomly on worlds like previous builds and instead you will find runes which you use on crafting worlds to create new spells. This gives you some early goals to work towards as different spells require different runes so you have to scavenge worlds for the rune types needed for the spells you want. Certain worlds will be easier to conquer if you have the right spells and certain puzzles might require a specific spell to solve.
A much-needed interactive tutorial has been added so anybody not already familiar with the old Magic Carpet games will now have the basic movement, combat and crafting mechanics explained to them. You don't get everything handed to you on a plate though so you still have to figure out what those circles are and what to do with them.
Several improvements to the map make locating items on worlds much more easily. Un-triggered circles are marked as are creatures and mana gatherers and there is a line back to your castle so navigating is much easier. In the universe map you can also check if you have missed anything on worlds you have visited which is pretty useful.
Difficulty has increased on v0.25 as your starting mana is now lower and you can't just rain fireball death on enemies right away so you have to fly more evasively until you have added some mana to your castle allowing you to sustain your fire rate for longer periods. Dark worlds are a new addition and whilst I don't want to ruin the surprise I will say that poorly prepared Wizards are going to have a bad time in these! One of my early criticisms of the game was that it was a little too easy and creatures offered no real threat to you which is now being addressed.
The game is also moddable which is fairly unusual for an alpha-build game. The scripts in the /gen/ folder are not only responsible for world generation but also the gameplay elements so there is a lot that can be done to tweak and customise the game. There isn't much in the way of documentation (or even comments) so the difficulty curve for modding is currently quite high but I expect this to change as the game develops further.
Arcane Worlds is a truly amazing experience for an alpha and I can't recommend it enough regardless of whether you ever played Magic Carpet or not.
I should point out that as the game is DRM-free many people (including myself) usually aren't logged into Steam when I play so the "played" hours count (3.5) is far from correct for me at least. I think I will have to change that!