I have been reviewing past age designs and puzzles, sorting through them and attempting to put them into context. I freely admit that I have not completed Revelations and End of Ages, mostly due to technical problems. In addition it has been many years since I played Myst, Riven, and Exile, as well as the original URU and PoTS. So without resorting to nitpicking, I hope you will feel free to submit additions and corrections of a substantive nature.
In the original Myst we were presented with only limited information to lead us into the mystery. We had a note from Atrus, some information in the imager by the dock, and burned books in the library. Two books in the library gave us a scratchy image of two men. There were three levels of puzzles -- the first was to open a place on the island to reach a linking book to one of the related ages. We then had to find the power source to "turn on" the age and to use the access to acquire one of the two pages. The third level of puzzle was to find the wretched linking book to get back to the library >grrrrr< (I am very fond of my Relto book and never go anywhere in the Cavern without it ) Then we had to do it again to obtain the second page. The issue quickly became an assessment of the two men, based on clues presented by their choice of decor, comments found in the journals, and eventually what they say as the pages give them more voice.
The first novel added to our understanding so that we were ready to deal with Gehn in Riven. While the puzzles could be maddening, the story drove us to uncover more. Because of the mostly non-linear design we could complete ages in no particular order for the most part. Certainly by Exile the training ages could be done in any order leading to the same result.
Power Sources
The first thing we learn is that machines must be powered. This has been true in all the Myst worlds. So far we have seen steam, solar, heat, wind, gravity (counter-weights and flotation), current (water, electric, battery), amplitude and resonance (such as sound, although we should remember we have tone-deaf and other hearing-impaired players for whom some accommodation should be made, such as a sound frequency meter), crystal shape and color (again, for those players who are color-blind or have other vision problems we should incorporate a color specification device such as those used by photographers and lighting specialists), pressure (geo-thermal, water, air), and the list goes on. We have also had nature's assistance whether it is from a squee in Exile or fireflies attracted to our natural body current.
Doors and Locks
The goal of many ages is to open a door and the reason we can't is because it is locked. Unlike the power issue, a lock must be opened by a series of steps which must be performed in the correct order and at the right time to get the door opened. Despite the many doors we must open, I can distill this down to two types: IC doors and OOC doors.
An IC door is locked because some element of the story requires it to be. The best examples can be seen in Kadish Tolesa and Ahnonay, both because Guildmaster Kadish did not want outsiders getting into his secrets. An IC door not only gives us great puzzles to solve, but the feeling that it is all organic to the age and to the story being revealed.
An OOC door is locked because it serves a purpose to the game that is external to the story. The best examples are Tsogal and Delin. The complex nature of the timed combination lock seems out of place just to get to a bahro cave and the stone ring within. In most of the other bahro door ages we collect cloths. In the prime ages these are part of Yeesha's request to learn about the plight of the bahro. Tsogal and Delin, however, serve a valuable OOC purpose for an online game based on an older solo game. They require teamwork to solve. In the earliest days of MOUL these two ages got people together and so they served an OOC purpose.
Light Portals
In addition to the bahro cave doors, we have light portals. These include the timed portals in the four pod ages, as well as those that are built one symbol or cloth at a time. The pod portals are all the same, but the rotational nature is well-done. With players in so many time zones the portal will eventually appear at a time convenient to everyone -- with a lot of patience and persistence. My greatest hope for the pod ages is that we see more through the windows or that at some point we can exit the pods with surface access (Negilahn and Payiferen).
Those light portals that are built one symbol at a time are in two forms at present. In Minkata, we touch a stone in a cave, follow a constellation to a light symbol and follow it back to the cage, where touching the stone there locks that part of the portal into place. Ercana and Ahnonay, both from PoTS, have the same quest as the prime ages to collect 7 cloths. The difference is that you can not see the progress on the cloths, only at the stationary point of the portal. While this is visible in Ercana, in Ahnonay you can not see it until you get to the last cloth. In this latter age, if you have missed an earlier cloth you will have some problem if you come up part of shell short.
Eyes on the Prize
In some cases we know what we are attempting to achieve by working through an age. In the prime ages we have been given a "request" by Yeesha to learn about the bahro. In the original solo game it was a matter of collecting and returning pillars. Now we also get a rock ring on an unwieldy stack on Relto. So far no one has defined what the rocks are for or what they mean.
In the more recent ages we get a rock ring, and maybe some spiffy piece of clothing, but have we gained more knowledge about the world we love so much? I would like to see knowledge of the D'ni increased by completing an age rather than just another level to the stack. One of the great charms of the earlier games was to have the story revealed with each move forward. This means that some content writer had made a story line, researched and defined to the age creators, that was incorporated into each age. Consider what we learn about the D'ni from Yeesha throughout the cleft and prime ages. This is the purpose of backstory and the revelations carefully placed so that we learn a little, but not enough to overwhelm us. It should be a prize sufficient to whet our appetite for more.