Saturday, June 28, 2008


Title: Skyscraper
Author: James Smith (me)
License: Creative Commons

Recently, cynthia posted a comment to an old entry on Japanese Puzzles asking,
do you know, where i can found the printable version for japanese puzzle?
As It happens I have been working on a set of skyscraper puzzles. For reasons I do not understand, I really like these puzzles, but they are hard to find. So, I wrote a program to generate them. The program produced a TeX document which resulted in the pdf document linked to above. You can download it and print it out.

In a skyscraper puzzle, you have to fill each square with an integer from 1 to n where n is the size of the puzzle. No number many appear twice in any row or column. The numbers along the edge of the puzzle give additional constraints. They indicate the number of buildings which you would see from that direction if the row or column was converted in a series of skyscrapers with heights equal to the entries. For example, consider the row 1, 4, 5, 2, 3.

From the left, buildings 1, 4, and 5 are visible. So, the clue would be 3. From the right, buildings 3 and 5 are visible giving a clue of 2. Here is a completed puzzle.

There are 100 puzzles ranging from 4 by 4 to 7 by 7. I have assigned a one, two, or three star difficulty to each. This is only a rough guide. Have fun.

To further answer cynthia's question, the site provides printable puzzles for several puzzle types:
That should be enough for most people.

Saturday, June 14, 2008

Rant: Game Reviews

An interesting news story made the rounds last week. It concerned Electronic Gaming Monthly choosing to not review the prerelease version of Metal Gear Solid 4 due to the excessive limitations imposed by the publisher. The sequence of events does something like this. The review magazines want to get the reviews out about the same time that the game is released. To do this, they need access to a prerelease version. The lead time on publishing most magazines is over a month. In order to gain access, the magazines have to agree to certain limitations. But this time, in this case, the limitations were too severe. Thus the story.

First, a little background on me. Before turning into the cranky old man that I am today, I was once, like 15 years ago, a hardcore PC gamer. And I loved my gaming magazines. Do you remember those four page reviews in Computer Gaming World with more words than pictures? I used to devour those magazines. I used to buy the British version of PC Gamer for a different perspective. I ate it all up. I was so naive.

In reading various accounts of the EGM/MGS4 story and related forum posts, I noticed that no one seemed bothered by the fact that there are ever limitations imposed on the reviewers. Everyone seemed to praise EGM for making a disciplined stand here. All I could think, how could they ever agree to any limitations on any review in the first place. Every review in EGM is now tainted. At the very least they should disclose the limitations at the beginning of the review.

Every game review magazine does this, and they have been doing it for a long time. So, it is unfair for me to single out EGM. Worse, my beloved Computer Gaming World became Games for Windows few years ago and was jointly published by Microsoft. Basically, it became a PR rag for Microsoft and people stopped buying it. The print version died in April of this year. No one shed a tear.

For me, the end of game review magazines came with the PC Gamer review of Diablo 2. The reviewers were only allowed to play the prerelease version at Blizzard's site on Blizzard's computers. They gave it a great review. When the game was actually released. It was buggy. The usual stuff: it would not work with certain video cards, etc. I, and many other people, happen to have one of those cards. It was very standard video card, but I cannot remember which one. At that point, PC Gamer became worthless to me. I quickly canceled by subscription. They forgot who their customer was.

In the end, Blizzard patched Diablo 2, and the patched version is a great game. But the game I purchased would not run on my computer, making it one poor game. PC Gamer took some flack but did not make any real changes.

My other big complaint about the reviews was the lack of information on copy protection. They would have the occasionally have a story about how annoying copy protection is or a fluff piece on the evils of StarForce. But, what they would not do is just list in the info box for each game, along with how much disk space it needs, the method of copy protection. That would have been great for us, but would have pissed off their masters. Once again, they forgot who their customer was.

The lack of objective reviews has really hurt the PC gaming industry. As much as car makers might grouse about a bad review in Consumer Reports, they know that having informed consumers actually helps their industry. Customers feel more confident that they are making the right purchase and thus make more purchases. PC game publisher's failed to understand this.

Maybe I am just bitter that puzzle and logic game fell out of favor.

Sunday, June 08, 2008

Next Element

Title: Next Element
Author: Zielock Games
License: Freeware (donation requested)

Next Element is similar to Hex-a-hop and MASRDBE. It is not as good as the former, but better than the later. The object is to find a path from the start tile to the goal tile which passes through each of the numbered tiles that many times. There are two additional twists. First, the arrow tiles can only be entered from the tail of the arrow and exited in the direction of the arrow head. Second, there are teleporter tiles which jump you to another part of the board. An oddity of the rules is that these special tiles can only be used once, but you do not have to use them to complete a level.

There 30 levels which must be played in order. The level design is decent. Most of the levels are easy, but there are a few tricky ones. One key features is an unlimited (I think) undo feature. One minor misstep does not require a restart of the level, just hit 'u'.

The interface for Next Element is straight-forward, use the arrow keys. The graphics are simple but effective. I found the audio a bit annoying and turned it off . These is not much else to say. It is a fun freeware game worth playing if you like these sort of puzzles.

There is no level editor. If you make a donation to Zielok Games, they will allow you download Next Element Deluxe which contains 80 levels.

As I mentioned in my entry on MASRDBE, solving these puzzles comes down to finding a Hamilton path in a certaom graph. In any position, there are at most four ways to move and usually far fewer. Also, it is pretty easy to notice when things have gone bad. For example, the remaining tiles are disconnected, or there is a dead end. So, I am guessing that a depth-first search should do really well on these problems. Maybe a meet-in-the-middle search is needed for some problems. I am curious if a computer search could find some really tough puzzles. I am sure, as the size of the board increases, the problems become exponentially hard, but with 10 minutes thought I could not see a proof that they are NP-complete.