Today: Improving movement around corners in Gonna Catcha. Tomorrow: Humour check-up

In my various playtests of Gonna Catcha, I have noticed that many players were having difficulty trying to turn at intersections, going from one corridor to another perpendicular corridor. The solution I came up with was simple, yet I still managed to write this whole blog entry about it, so here goes.

Gonna Catcha uses a smooth, grid-based movement system, as in, even though the players move smoothly, they will always be aligned with the grid that divides the play area when stopped. This is to facilitate players in lining up properly intersections and going around wall corners, instead of having the player painstakingly line themselves up with pixel-perfect precision. Even with this alignment aid, I’ve noticed in my playtests that players were still having problems negotiating those corners.
To explain this better, below is a figure showing five different cases where a player is approaching an intersection (click on it and any other figure to expand):

Figure 1. Five cases of a player approaching an intersection

The figure shows two horizontal corridors linked by an opening between them. In cases 1 and 5, the player is not aligned with the opening; in cases 2 and 4, the player is partially-aligned, and in case 3 the player is fully-aligned.

The next figure shows what happens when the player holds [Up] to try to move upwards in each case:

Figure 2. Results of holding [Up]
As expected, in cases 1 and 5 the player cannot move upwards since they are completely blocked by the wall; and in case 3, the player is free to move upwards since there are no obstructions in the way. The problematic cases are 2 and 4; where the player is partially obstructed by a wall, which for all intents and purposes counts as being fully-obstructed by the game. In most of my playtests, players end up in cases 2 or 4 when they try to turn too early, and they end up getting snagged in corners, which was a bit frustrating to them.
For a long time, I’ve thought about whether to fix this problem, or just leave it in as a “quirk” of the game’s movement system that players need to get used to in order to get good at the game. Many games in the 1980s did have control schemes that had quirks or little annoyances that players needed to learn to in order to master them (I’m looking at you, Bubble Bobble, Ice Climber and Super Mario Bros.).

One day, out of boredom, I found my copy of Midway Arcade Treasures 2, an emulated collection of old Midway arcade games. I only played it a few times on my Gamecube a long time ago, so I decided to give it another chance and popped it in my Wii. After chopping down trees in Timber and crashing cars in Hard Drivin’, I played a game that caught my attention: Wizard of Wor, an action maze game from the magical year of 1981:
The basic premise of of the game is you and a partner must shoot and kill all the monsters in a maze-like dungeon to move on to the next one. The partner can be another human player or, if you’re playing alone, a computer player with limited intelligence. From what I’ve seen, the players’ movements aren’t confined to a grid like in Gonna Catcha. However (and this is the whole point of me mentioning this game in this post), the game had no problems with players getting caught in corners, as the player characters would “hug” the corners if they were close enough to one. In technical terms, the player would move in the direction perpendicular to the direction the joystick is being held, towards the nearest intersection if one was close enough. Confused? Don’t worry, there will be figures soon.
This got me thinking, if an actual early-1980s arcade maze game could handle intersections like this, then Gonna Catcha should be able to too. So I modified the movement code (something I haven’t touched in a long time) to make it handle corners and intersections like Wizard of Wor (and likely the multitude of maze games that came after it). The figure below shows the results of holding [Up] in each case with the new movement system:
Figure 3. Results of holding “Up” in the new movement system
Cases 1and 5 remain the same, however in cases 2 and 4, the player will now scoot around the corner of the nearest intersection if they are partially-aligned with it. Playtesting the game with the new movement system, I can say for certain that turning around corners is now much easier and smoother. One other thing I noticed when I was playtesting was that I had coded the movement direction and the way the sprite faces independent of each other. Before this change, the player’s movement and facing were always in sync, so I never noticed it, but now that there are cases where they’re not in sync, and in those cases it looks like the player is sidestepping or strafing around a corner. Technically, this is a graphical glitch, but I think I will allow it, because it looks cool.

The v.0.9.1 update will be coming soon. It’s not the finalized version of the game, the later levels are still unbalanced and possibly impossible to beat, but I am one step closer to it.

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