Before I write my review, I thought it might be useful to supply some relevant information regarding myself, and my preferences/expectations with role-playing games. I have been playing role-playing games for 30 years. I have played many RPG systems including AD&D, Palladium, GURPS, Everway, Cyberpunk, Villains and Vigilantes, Traveller, and D20. I have probably spent equal time playing and hosting. I have made three versions of a simple one die system myself.
I generally prefer games that favor role-playing and story over tactical combat, but when both are done well, I am extremely pleased with the result. My experiences as a player and GM lead me to believe that the people, not the system, are the most important ingredient for a good role-playing experience.
I am saying all of this not to establish myself as an expert, but to reveal any biases that I might have when creating a review.
When I review Elthos, I think I will consider the following: complexity, ease of play, and variability.
Complexity
Elthos has a learning curve, but all systems do. What are Mystic points and Life points? What is DAB, and TAC? How do you roll a critical success or failure? How does combat work? Believe it or not, there are simpler systems out there, but for the most part, these concepts are pretty much what you would expect from any role-playing game. There are formulas in Elthos, and that scares some people, but, since Elthos exists as a web application, it handles all of that instantly. I believe that there is also a print out that people can use with all of the terms and formulas in a nice tidy list to use while playing.
On the other hand, Elthos is far from the most complex system out there. There are no comprehensive rules for aiming for body parts, disabling body parts, blood loss, aging, how long you can hold your breath and the infinite number of other possibilities that can be encountered in a RPG.
On a scale of 1-10, with 10 being the highest, I would score Elthos' complexity at a 5 because of the handy online software.
Ease of Play
To call a system "easy to play," I am looking for one where players don't need to constantly refer to the rules to take action. Elthos scores high here because of two things: Elthos doesn't have a rule for every scenario and it handles action resolution consistently. Since there isn't a rule for everything, it is expected for the GM to resolve actions with common sense and the tools available.
This gives players the freedom to try anything and it frees everyone from looking up a rule, or potential rule, when playing the game. This is a double edged sword. Some people want a role-playing game to fairly simulate their game's setting. They want a rule for how much dirt can be dug by a character with X strength in one hour. GURPS has a rule for that. Some people like that. Some people realize that no book can have guidelines for all the possibilities that can happen in a role-playing game.
Elthos is for people who don't want a rule for every situation. Its design doesn't want people to refer to the instructions during a game because it ruins the story's flow. It does a great job with that goal in my mind.
On a scale of 1-10, with 10 being the highest, I give Elthos a score of 8 when it comes to ease of play. Keep in mind that I would probably never give out a 10. Since there are systems out there that are even simpler than this one die system, I didn't give it a 9.
Variability
Very often, people who role-play, play different games which usually span different genres. Within the last twenty years, systems like GURPS, Palladium and D20 have established systems which maintain their core rules while adding the elements of different genres. This is a great feature because you don't have to learn a new set of rules just because you would like to try something a little different. Elthos has infinite varieties, but at a cost, since Elthos' variety relies completely on its users. Elthos allows its users to add their own locations, classes, feats, skills and equipment. It comes with basic fantasy fare, and even some sci-fi stuff, but that's it.
For a GM who loves to build a world, Elthos is the best way that I know of to build it in an orderly way. I have yet to build my own world in Elthos, but I've seen an Elthos GM's world and the way that Elthos keeps track of everything is astounding. I have run a D20 fantasy game for close to a decade. Sure, I used a computer to write up my adventures, but I still lost track of where adventures took place, items and characters. It would be really hard to mess it up with Elthos, but I suppose that if you tried really hard, you could do it.
On a scale of 1-10, with 10 being the highest, I'd give Elthos a 9 for variability if you're the type of person who likes to do it yourself. Keep in mind that the final vision of Elthos has the potential for people sharing their worlds. This means that Elthos could score the theoretical 10 here if there are enough users who are willing to share their work.
I have two more points to bring up that don't quite belong to the above categories. The first is the alignment tracking in Elthos. I have seen this system used in games like Neverwinter Nights on the PC, but I haven't seen it elsewhere in tabletop role-playing. A GM in Elthos can track how a character's alignment shifts. I find this refreshing and innovative since most games allow players to select an alignment, and then trust the player to stick to it. Rarely will it change. In Elthos, the GM may choose to rate every action and assign a chaos/law or good/evil modifier. When this happens, you might find your alignment shifting. This might not have much of an affect outside of a fantasy setting, but I find this fascinating.
The last point refers to the creator of Elthos. Mark is a role-playing nut. I am too. He loves to run a good game and even writes up the resulting adventures into full fledged stories. He gets what role-playing is about. This means that his love for the hobby can't help but spill over into the product. He has been working on Elthos for a long time, and I suspect that he will never finish it to his complete satisfaction, and that's what will make it great.