Discussion on game rules

In week 7, we had plenty of homework to do and thus we did not have time to write program code. Therefore, we manage to review the things that we have done up to now, and later found out that there is a big problem related to our game’s rule, and so we write these paragraphs to express what exactly is the problem.

I think nearly all the gamers would choose the game rules (how to play the game) as the essence of a game. As a programmer, the game rules are also his/her main concern. It is because game rule can affect the difficult of the implementation, the simplicity of the game play and the value of the game. When we were discussing the rules of our game a few weeks before, we did not consider much about the above issues. We only focus on the uniqueness and attraction of the rules, and did not think about the effects of a particular set of game rule to a game. Now, we are going to analyze all the set of game rules that we proposed before, discussing their pros and cons in detail.

The foundation of our game is built by a rectangular frame, where there are lots of monsters inside the frame. All the monsters have square in shape, and are packed nicely within the frame. The main target of players is to move the monsters so that several monsters of the same type are linked together. The linked monsters are removed, and new monsters come to fill in the empty space. Base on this game foundation, we can think of lots of way to complete the game. The game rule involves the following things…

1. How to move monsters
2. How to set the timer
3. One move → at least one match???
4. How to fill up the empty spaces after a match
5. How to set up different levels

…and we want a set of game rule that is easy to implement, easy to play and practical. In the following parts we would explain all the proposed rules one by one and finally we will tell our choice with the reasons behind. For each set of game rule, we first talk about the above five elements, and then discuss the pros and cons of that set of rules with reasons.

• “Swap”

1. Players are required to select any monster inside the frame first, and then select a second monster which is next to the first monster (up, bottom, left, right). Afterwards, the first monster move to the position of the second monster, and the second monster move to the position of the first monster.

2. There is a gauge indicting the amount of time left. If the time is over, the game is over. Extra time will be given to players once they succeed finding out a match.

3. If there is no match after swapping, the two monsters would go back to their original positions. Therefore, it is not allow completing a match after more than one swapping.

4. Once, there is match, the monsters involved must be removed. The empty spaces left are filled by the monsters above the empty spaces. It just the same as the situation happened in real life. Something will drop if there are nothings below it. New monsters arrive so as to compensate the loss of monsters which are removed after a match.

5. In each level, a set of number are set which represent the number of matches required for each type of monsters. In order to go to the next level, players must achieve the requirement before the time gauge becomes zero. When the players go up to higher level, the required number of matches increase, and the time gauge will drop faster.

Pros: This set of game rule is very sample. The program codes to handle swapping, detecting matches are easy to write.

Cons: This set of game rule is already implemented by quite a lot of game, such as Zoo Keeper, Diamond-Twister, Jewel Quest®, etc. Handle the falling of monster to the empty space is quite complex. The game program need to keep checking whether there is at least one possible move that can result a match.

• “Pick and Push (1)”

1. Players first select a monster only from the edge, which means that only the monsters that is not surrounded by four monsters can be selected. This action is called “pick”. Afterwards, an empty space is left. Players then need to “push” the picked monster back to the frame, starting from the edge again. For Example, sixteen monsters group around to form a 4×4 square. Since only the monsters at edges can be picked, the four monsters at the center are fixed. The following is a simple graph showing the map of the sixteen monsters, where only the monsters marked with symbol (o) can be picked up, while the monsters marked as (x) cannot be picked. (+) is the frame.

++++++
+oooo+
+oxxo+
+oxxo+
+oooo+
++++++

If a monster (m) at the edge is picked like the following…

++++++
+oooo+
+mxxo+
+oxxo+
+oooo+
++++++

The (s) are the positions where the monster can be pushed back…

+s++++
+oooo+
+mxxos
+oxxo+
+oooo+
+s++++

After the push, the monsters on the same line will be shifted together.

2. There is no global time gauge. On the other hand, each monster would have a local time gauge. When a monster firstly arrives inside the frame, a random value is assign to that monster. This value is just the time that the monster can live. The timer of a monster stops once the monster match with others. The game is over if there is one time gauge of a monster inside the frame dropping to zero. The time gauge of each monster will increase its value once players succeed finding out a match

3. If there is no match after shifting, all the shifted monsters would go back to their original positions. Therefore, it is not allow completing a match after more than one shifting.

4. Once, there is match, the monsters involved must be removed. The empty spaces left are filled by the surrounding monsters. In another words, the empty spaces will be filled by shifting the monsters from either north, east, south and west direction. New monsters arrive so as to compensate the loss of monsters which are removed after a match.

5. In order to go to the next level, players need to achieve the number of matches set by the current level. For instance, in level one, players must find out at least 20 matches in order to go to the next level. In level two, 40 matches are required. In level three, 80 matches are required.

Pros: As we know, no one implements this. This game rule would create more variations compared to the “swap” rule. The way of making a matches in the “swap” method is direct, while it is indirect in this “pick and push (1)” method; Players need to think a little bit for finding out how to shift the monsters in order to obtain match. This game rule also gives players more thinking space how to move so that there will be another possible matches waiting for players. The new timing method seems to be much better than the traditional global time gauge.

Cons: It has the same cons that the “swap” rule has. Handle the shifting of monster to the empty space is quite complex. The game program need to keep checking whether there is at least one possible move that can result a match. Also, player cannot find a way to link the following monsters (e) together. (o) can be any type of monsters.

+++++++
+ooooo+
+oeoee+
+ooooo+
+ooooo+
+++++++

The “swap” rule allows players to match those monsters.

• “Pick and Push (2)”

1. This set of game rule is the same as “Pick and Push (1)” rule except one thing. Any monster can be picked inside the frame. Let’s see the above example where the monster (e) cannot be linked.

+++++++
+ooooo+
+oeoee+
+ooooo+
+ooooo+
+++++++

The monster at ($) is picked, and is pushed at (#).

+++++++
+ooooo+
+oe$ee#
+ooooo+
+ooooo+
+++++++

2. 3. 4. 5. Same as “Pick and Push (1)

Pros: It solves the problem shown above.

Cons: It seems that there is a loophole in this rule. Let’s consider the following example. (o, a, b, c) can be any type of monsters.

++++++++
+ooo#oo+
+oo$ooo+
+o$c$oo+
+ooaooo+
+oo#ooo+
+oobo#o+
++++++++

Considering the monsters ($), we can link up them by picking a monster (#)

++++++++
+oooo+ \\ +oooooo+ \\ +o$$$oo+ \\ +oooooo+ \\ +oooooo+ \\ +oooo#o+ \\ ++++++++ \\ If the empty spaces of the monsters ($) are filled by shifting monsters along the east direction, the map becomes this. ++++++++ \\ +oooo+
+oooooo+
+oooooo+
+oooooo+
+oooooo+
+oooo#o+
++++++++

It is clear that players can obtain another match next. This is the trick that players can apply in the game, and it significantly reduces the interest of the game.

• “Pick and Push (3)”

1. In this set of game rule, players need to select one output arrow, and one input arrow, where the arrows are located around all the monsters. The monsters will shift according to the input and output arrows. For example, let (i) stands for input arrow, and (o) stands for outputs arrow.

++++++++
+nnnnnn+
o1nnnn2i
+nnnnnn+
++++++++

The whole line will be shifted to the left. A randomly assigned monster will come behind monster (i).

2. 3. 4. 5. Same as “Pick and Push (1)

Pros: Player will no longer be able to play tricks any more.

Cons: It seems that shifting an entire line is very straight forward.

• “Pick and Push (4)”

1. This game rule is extended from the “Pick and Push (3)”. Now, players are able to shift monsters not only in one straight line, but also in two straight lines.

++++++++
ossssnn+
+nnnxnn+
+nnnxnn+
++++i+++

Monsters (s) will be shifted to the left first, and the monsters (x) will then shifted to the north in order to fill up the empty space.

Pros: The game rule does not seem to be straight forward, and there are lots of variations in real time.

Cons: We have imagine the actual game play of this approach, and we finally conclude that this rule create lots of variations that would cause confusion to players, and players may need to take some time to adapt this game rule, although this game rule does not seem to be complex.

In fact, we have other set of game rules related to the “pick and push” approach, but they are not better than the one describe below.

• “rotation”

1. Players first select a monster in the frame as the center of rotation. Then, players should choose the direction of rotation, either clockwise or anti-clockwise. Then, the monsters surrounding the monster at the selected center are shifted according to the direction players desired. Let’s see an example. Monster (5) is selected as the center, and the surrounding monsters (1, 2, 3, 4, 6, 7, 8, and 9) rotate in clockwise direction.

+++++++
+o123o+
+o456o+
+o789o+
+ooooo+
+++++++

After rotation…

+++++++
+o412o+
+o753o+
+o896o+
+ooooo+
+++++++

It is possible to select a center at the edge, as there are monsters hide behind the frame. In another word, the (+) symbol are in fact be considered as monsters, but they are not visible to players.

2. Same as “pick and push (1)”

3. If there is no match after shifting, all the shifted monsters would not go back to their original positions. However, there is limitation. There is a value indicating the number of false rotation (no match after rotation) allowed. This value can increase if players satisfy some extreme condition, and it decreases when players perform a false rotation.

4. The empty spaces are filled by simply putting a monster randomly assigned back. So, there is no any shifting of monsters. This approach does not reduce the variations of the game, as the rotation part would trigger some variations.

5. Same as “swap”

Pros: It game rule does not have the cons discussed above.

Cons: It is not possible to link up the monster with the same type if they are located like the following map.

+++++++
+oxooo+
+xoooo+
+xoooo+
+ooooo+
+++++++

However, since the above case does not happen frequently, therefore, this drawback does not have significant impact.

We finally choose the “rotation” game rule, which is the best up to now.

Achievement in Week five

Originally, we plan to use image with size 32×32. Since the width of screen of iPhone is 320, we can put at most 10 monsters' images per column in landscape mode. Later, we realize that the images are too small (The size of simulator is much bigger than that of iPhone). So, by referring to other similar iPhone games, we finally choose 40×40, and there will be 10×6 monsters on the screen.

Later week, we said that the images shown on iPhone simulator are darken and blurred. In week five, we succeed in improving the quality of all images. First of all, all the monsters' images are enlarged so detail can be displayed clearer. Secondly, the images colors are sharpen, and the contrast rises a little bit. This compensates the blur effect. We both believe that the image quality is very important to a game. Therefore, we will continue improve it, and we want all image can become better after each change.

We disclose the interfaces of our code last week. In fact, it is not complete. When we continue writing our game code, we found out that there are lots of things needed to be added or deleted. We think that the interfaces would not be fixed before the game is released. So, we decide to upload the source code instead of posing it on the blog.

Finally, the game rule of our game is slightly change, and this change does not affect our game development process. We make this change in order to prohibit players to do any tricks. We are not going to tell the detail here as lots of words are needed to write.