keskiviikko 22. huhtikuuta 2015

Steam It or Leave It - GDD Project

1         Introduction

1.1       Overall

The game is a 2D side-scrolling beat’em’up with a focus on knockback, knockup and knockdown delivered by the player’s steam-powered arms and legs. Most of the levels consist of fighting through hordes of enemies and utilizing the varying knockback from each attack. Visually and gameplay-wise the aim is to be as bombastic as possible in a 2D space while still maintaining responsive player control with instantaneous input registering and fast animation. While a lot of beat’em’ups have a few enemies at a time, the aim is to allow for things like downing a row of 10 enemies with a well-placed punch.

1.2       References and inspiration

I draw a lot of inspiration mainly from 2D sprite based game companies and developers. Vlambeer have provided many great ideas on making a game feel good both visually and gameplay-wise with their games Nuclear Throne and Super Crate Box. Said games have snappy and simple controls and nothing about the player’s movement feels sluggish or unresponsive. They still have visual flair and spectacle though, with the screen sometimes filling with projectiles in Nuclear Throne. Most of the time this adds to the game feel and only in rare cases does it become distracting.

A surprisingly good game feel can be found in One Finger Death Punch. Every time you send an input the game’s reaction is instantaneous and the animations do the same. The game can thus deliver fast paced action without the player ever feeling that the game is to blame for a death. Only two buttons are needed to play: left and right. This kind of simplicity does have its perks, as a really complex control scheme does understandably put a lot of gamers off.


2         Development tools and technologies

2.1       Technical implementation

Unity is the engine of choice, as it provides a good 2D toolkit that only got better with version 5. The engine is easy to use and accommodates rapid prototyping really well. While the ability to port to other platforms easily is a nice one, the initial focus is PC. If selling the game is ever considered, the free version of Unity can be used without fees or royalties until a treshold of $100 000 annual revenue is passed. Input is given digitally with either a keyboard or any controller with a D-pad and 2 action buttons.

2.2       Graphical assets

Graphically the aim is to use raster sprites, since they can be downscaled to a certain point to boost the performance, whereas it’s harder with vector graphics. The attack animations should convey the punch or kick directly in the first frame, only using the remaining frames for smoothing. This ensures that the player attacks instantly when he wants to, and the attack detection is much easier to handle. Flash Professional CS5.5 is used to create the rough animations, which are then either cleaned up in the same program or with a raster painting tool like Manga Studio 5.0. If necessary, outlines may be done traditionally in ink and scanned in for coloring.


3         World design

3.1       Setting

The game is set in a western frontier town and the surrounding desert. In the wake of the industrial revolution, steam power has seen widespread adoption, mostly for mining. Massive mining robots and exoskeletons were a boon for the industry, but they soon found a use in more dubious circles. Outlaws found these constructs to be easily repurposed as mobile fortresses to control the area. As a response, the law had to do the same, elevating the traditional shootout at sundown to an all-out war between bronzen machines of destruction.

Steam machines have found their uses in everyday life as well. These powered creations have given the protagonist new life in the form of prosthetics. Geared towards mobility and overall surpassing of the regular human body, these new limbs give him the power to perform superhuman feats e.g. jumping to new heights and giving pesky outlaws a free ticket to the next county with charged up punches.

3.2       Enemies

The enemies mostly consist of outlaw grunts. The most basic ones only use melee weapons like pickaxes or firearms like revolvers. These enemies are considered throwaway enemies in that the player will usually dispatch them rather easily. They only pose a threat in big hordes. Harder variants include specialized enemies such as ones equipped with dynamite or gatling guns. They tend to require nailing down a certain pattern, such as jumping over gatling gun bursts or hitting the dynamite back before it blows up.

The real challenge is delivered via boss enemies wearing steam-powered exoskeletons and eventually piloting giant, mobile, steel fortresses. These bosses and minibosses always bring with them a new combat pattern or interaction to learn. As the player can respawn and try again pretty much instantly, they can easily take a few tries to get through. They use existing interactions with the combat engine e.g. knocking grunts back to hit an artillery piece on the other side of a ravine or knocking grunts upward to unbalance a walking fortress.

3.3       NPCs

The NPCs mostly play a supportive role, selling the player upgrades to their gear or new gear altogether. They are mostly found in towns, which the player can access between levels. They can also be rescued from the outlaws in certain missions for monetary and gear rewards.


4         Gameplay

4.1       Main game mode

The game plays out in two different screens: the map screen and the action screen. The map screen is a top-down view of the land and acts as a hub to all the different missions and levels in addition to the towns. The action screen means the missions themselves. The aim is to beat all the missions with various objectives and bosses.

4.2       Controls

The game is controlled mainly with a keyboard, but as the game handles only digital input, a controller should work easily too. The only buttons needed are for the movement, and two action buttons: one for jumping and one for attacking. An example control scheme could use the arrow keys for movement, the X key for jumping and the C key for attacking.

4.3       Movement

The movement works in a traditional platformer style. In addition to moving horizontally, the player can also jump, crouch and, by extension, slide by crouching while moving. The horizontal movement doesn’t have any inertia, so the player starts and stops moving instantly.

4.3.1       Jump input buffering

To avoid the platforming becoming annoying, the player can jump a few frames after they break contact with a platform. This allows for long jumps being worked into the level design without them becoming too much of a challenge or feeling unfair. It also allows the player to press jump just as they see theirselves landing on the ground, even if the engine still thinks they are in the air.

4.4       Combat

All different movement states have attacks in different directions where possible, as seen below. This is to ensure that the player has a good amount of control over his character and doesn’t feel frustrated with limiting attack directions.


An attack always stuns the enemy for a few frames, keeping them from getting sucker punches through in-between the player’s attacks.

4.4.1       Attack input buffering

To allow for basic attack combos, the player may buffer attack inputs. This means that the player presses the attack button to initiate an attack, then presses it again while the first animation is playing. This then triggers the next stage of the combo and the player may continue on like this. This also works when transitioning from a preanimated combo to another attack.

4.4.2       Combos

Combos refer to chains of attacks executed in rapid succession. This includes buffered attack combos and also basic attacks chained together to keep enemies stunned. Anything that damages or knocks an enemy back, up, or down counts toward a combo. This might be used at some point for powerful special attacks, but for the first version it just adds a multiplier to gained points.

4.4.3       Hit points

The player and the enemies have a certain amount of hit points, which protect them from getting knocked back. These don’t regenerate over time, but the player does regain them with long enough combos.

4.4.4       Dizzy

After the player’s or an enemy’s hit points are depleted, they enter the dizzy state. In this state they are vulnerable to a knockback. For a player this means that a full enemy combo will knock them out, triggering a respawn. For an enemy, however, this means that any player attack will send them flying a certain distance through the air, knocking down any enemy they pass through. After landing, they are knocked out and despawned.

4.4.5       Knockback, knockdown and knockup

A big focus of the game is the ability to knock dizzy enemies around and use them as projectiles of sorts. This can be used to knock down other enemies, or to damage bosses from range. This also adds a strategic element to the gameplay, as area-of-effect attacks with the ability to stun or knockback enemies can be used to control hordes of enemies.

4.5       Points and money

In score attack modes, the player is rewarded points for each attack and damage delivered. The points awarded are always increased according to the multiplier calculated from the combo count. Enemy knockouts also award points. This is replaced completely in the story mode with money that the enemies drop. Money can also be found in crates, chests and other containers scattered about.

4.6       Upgrades

The player can use the money he gathers on missions to upgrade his gear back at town. These upgrades provide new abilities or upgrades to existing ones. The new gear also changes the player’s appearance to reward him further.


5         Screens

The main game consists of two primary screens: the map screen and the action screen. The map screen contains a visual representation of the area and acts as a level select. The action screen contains the core gameplay. The shopkeepers in town have their own shop screens, showing item statistics, monetary info etc. The main menu only needs to contain buttons to start the game, to change options and quit the game. This is because the map screen already provides a space in which the player isn’t required to react to things in real time.


6         Testing

Testing will mostly be carried out by letting friends and other students play the game. This is because the game doesn’t have all that many complex moving parts, reducing the risk of a killer bug to ruin the whole experience. Of course, after release, the game will be kept up to scratch, issuing bugfixes and hotfixes when needed.


7         Distribution

Depending on if the game gets to a point where selling it would be appropriate, it will first be released on itch.io. The site provides a quick and easy system for hosting free games or selling them. Upon checkout the buyer is always recommended to donate extra money if they want to. This creates a goodwill system, where the downloader can decide if the game is worth money. Of course, you can set a baseline price that they must pay to gain access.

If the game is to be sold, the Humble Store, GOG.com and Steam are always good options. The only real barrier might be the Greenlight system on Steam. The 100€ fee for it is rather negligible, but to get on Steam, the developer is required to do a fair bit of PR in the form of advertisement be it on a development blog or Twitter for example.

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