Unique fusion of a top down shooter and tower defense strategy. You are the X-Morph - an alien species that invades Earth to harvest its resources. Strategize in the build mode by carefully selecting various types of alien towers or throw yourself right into the battle. Build mazes for incoming enemies in an environment that provides exceptional planning freedom. Tear down buildings and collapse bridges to support your defense or to simply indulge in a spectacle of unprecedented destruction.

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Chinese Dragon Train Boss

Hello and welcome back to another episode of our series on boss fight design! It is actually the first time we are posting an article from this series on IndieDB, so if you are interested in previous installments visit our blog on Gamasutra - Gamasutra.com boss we showed you last time was relatively easy to implement and made it into the final release of X-Morph: Defense. The one we will be discussing today had no such luck. Made up of hundreds of little pieces, the task of making all the components work together turned out to be a little bit too much for us, given the time restrictions we eventually had to impose on ourselves. Let's take a closer look at it - here's the Chinese Dragon Train.

This is the untextured prototype from a very early stage of development.
Notice the scale of the train compared to a regular tank.

Even the sheer size of it is quite daunting. This boss was supposed to be the final enemy of the China stage in X-Morph: Defense. The battlefield is located in the middle of a military base. It is not unusual for the army to carry their freight by using specialized trains, so we decided it would be fitting and more unique than another ultra-heavy tank or a gigantic aircraft. Comprised of four completely different carriages, the Chinese Dragon Train had a number of ways to make the players sweat.


The entire Chinese Dragon Train would fill up a large portion of the level
and would be too large to fit on a single screen in-game.

As you might expect from EXOR Studios, the visual aspect of the boss design was rather over the top. The train with all its carriages spanned across almost half of the map. Since each part was specialized to carry out a different task, all of them had to vary significantly. That meant, of course, that our artists had to prepare 4 models to be later connected into one consistent entity. It was a tall order, especially given the fact that all the parts had completely different purposes.

The parts of the train were connected by dynamic joints,
allowing it to slightly bend while making turns.

The Chinese Dragon Train is not just a vehicle packed with weapons. In fact, it is a military base on wheels, complete with an artillery cannon, a nuclear strike calling satellite dish and even an aircraft factory! A MIRV missile launcher rounds up the package nicely, giving the boss complete control over all the aspects of the battle taking place around it. There simply isn't an aspect of the warfare the train couldn't control.

The cannon carriage doubles up as an engine for the whole train.
It is able to move forwards and
backwards. It's better not to ask about the power of its engines.


height - 43.5m
width - 39m
length - 56.5m
total number of weapons - 17

The heart of the Chinese Dragon Train is the engine. It is powerful enough to set all the other carriages in motion. It is crucial that this part stays operational for the whole machine to function properly, therefore it is constantly protected with an energy force field. Nothing goes in or out of this one. If everything else fails, however, the crew can man the onboard defense systems. The one that is immediately noticeable is the electromagnetic cannon, capable of long-range attacks. It seems like it would be the most dangerous weapon on this carriage, but it is the least of your worries.

Each carriage has its own hitbox map.
The player has the ability to choose which elements they want to destroy.

Joining the fray are multiple cruise missile launchers. They are capable of firing a barrage at the alien core. The projectiles are quite slow, so they can be shot down by the player. Nevertheless, it is a daunting weapon. The carriage also defends itself by shooting at the alien fighter with its quad anti-air guns. Providing covering fire for the engine, their relentless fire is terrifying enough to drive even the most experienced pilots away. Rounding up the arms package are the grenade launchers and napalm cannons, both meant to dispose of anything the X-Morph might have put up on the ground.

The second carriage, holding the satellite dish. Nuclear strike detected.


height - 34.4m
width - 38,2m
length - 80m
total weapons - 19

The second carriage does not seem quite as dangerous as the first one, but don't let the innocent looks fool you. The massive chassis covers up the satellite dish which the train crew uses to maintain comms with the space station capable of launching nuclear strikes on unsuspecting targets. It is the main weapon this carriage has against the X-Morph, but it comes with a significant drawback. The data transmission is quite long and can be interrupted, giving players a chance to counteract. In addition to calling a nuclear strike, the carriage is equipped with side lasers, capable of targeting the X-Morph core, like in a classic drive-by. Add AA guns to the mix and you have a force to be reckoned with.

The ballistic missile launcher car. The train's cars would move on
a quadruple set of train tracks due to the trains enormous size.


height - 32m
width - 43.2m
length - 80m
total weapons - 23

The third carriage on the Chinese Dragon Train is a MIRV ballistic missile launching pod. Its main weapon is only capable of long-range attacks, so we chose three points on the map they would be launched from. The train would stop and open up one of the six silos, preparing to launch one of the warheads at the alien core. The whole process is as cinematic as it can be, with smoke, sirens and red lights flashing as the rocket is prepared to start. Apart from adding dramatic flair, it was meant to be a moment for the player to strike, disabling the launch and protecting their assets.

Each weapon system is controlled separately.
The number of AA guns on this beast was an absolute overkill.

The secondary anti-core weapon is swarm missiles fired from eight side launchers. They compensate their lack of sheer power with the numbers. This attack happens instantaneously, so the X-Morph must shoot down the missiles while they are traveling through the air. Apart from that, the carriage is protected by the usual - flak cannons, grenade launchers and miniguns against the alien fighter.

An airplane launch pad on wheels. What a time to be alive.


height - 31m
width - 43.5m
length - 80m
total weapons - 21

The last part of the train might yet be the craziest of the bunch. Aircraft carriers are some of the most terrifying naval vessels known to man, given their high range and firepower. No water units in X-Morph: Defense meant that if we wanted to have one, we would have to come up with a different idea for that. Therefore, we put an aircraft carrier on rails and made it a part of the Chinese Dragon. To make the whole thing even more obnoxious (in a good way) it serves not only as a launchpad for fighters but also as an aircraft factory! To cut the players some slack, the neverending air assault does not attack the core directly, its sole purpose is to attack the alien fighter.

The aircraft carrier is not defenseless without its birds.
The plasma cannons on the sides fire relentlessly.

The other weapon the carriage is equipped with is side plasma cannons, shooting balls of plasma at the core that cannot be shot down. The only way to stop them is to interrupt the charging sequence, which might be a bit tricky given the swarms of planes flying around, like bees around the hive. The usual defensive package of AA guns, miniguns, and swarm missiles makes sure that the factory is well protected against all kinds of X-Morph attacks. This rounds up the whole offensive and defensive package of the Chinese Dragon.

The whole package. Notice the purple elements - humans and planes.
They show the true scale of this monstrosity.


highest point - 43m
widest point - 43.5m
total length - 300m
total weapons - 80

In order to take the train down, the player would have to destroy all of the single carriages. Each carriage has its weak spots, such as capacitors, generators, and engines. The player may aim at the weapons in order to reduce their functionality, decrease the damage and increase the charging time. If you decide to go for the weak spots, though, you might be able to snipe the whole part of the train before it becomes a significant problem.


One of the limiting factors for designing such a machine is the fact it moves on rails only. It meant that the level would have to be designed specifically to address this need. We decided to place six train tracks on the level. The players cannot see what lies beyond the level boundaries in X-Morph: Defense. That, in turn, gave us a free hand to turn the train back, rotate it, and place it on a completely different track than it previously used. By simply teleporting the boss entity we avoided the necessity of creating a multi-kilometer rail network only to turn around the train of this size. This was supposed to show that the rail network was very complex and required the players to guard 12 points of entry in total.

A very early mockup of the level design. The whole environment is designed
to accommodate the regular enemy waves as well as the boss fight.

The layout of the train tracks couldn't be random. Had we simply put intersecting tracks on a flat surface, it wouldn't have made the fight any more fun, just unnecessarily complex. Thus, instead of opting for a flat, desert-like environment, we went for a series of tunnels and overpasses. This element made it to the final game, as it introduces multiple ways the players can shape the enemy paths and take the level on.

Moreover, for a little dramatic flair, the train tracks would not be empty at the start of the level. To evoke the feeling of the humans being surprised by the attack, there would be regular trains all over the map. As with everything in our game, the player could destroy them. However, a more epic assumption was that the player left them alone and the Dragon Train would simply bash its way through all of the ‘regular' trains. It came to rescue humanity after all; you'd better get out of its way!


A perspective view of the early prototype.

The boss introduction was to resemble action films of the late 80s/early 90s, with its over-the-top epicness and the general atmosphere. The train would arrive to the battlefield as the weapon of last resort, and you'd better get out of its way. It would destroy everything on its way, and if the player had blocked any tracks beforehand all the obstacles would be destroyed as well. Its initial point of entry was the tunnel track and it would begin the fight with a ballistic missile attack.

The entry and exit point schematics.

After all of the above, the train would start its routine of cruising along one of the tracks, launching an avalanche of attacks available from its current position, leave the map, choose a new entry point and do it all over again. The reason for limiting the number of available attacks on a track is twofold. First, you do not want to overwhelm the player. Second - the structure of the level, with all the height differences, overpasses, tunnels, would render some of the weapons useless in a couple of circumstances. You don't want to shoot rockets at a wall, after all.

In order for this fight to be fair, we had to put some limits in place. First of all, as you already know, the train would follow 6 tracks with a total of 12 entry points. The attacks used by the train were determined by the point of entry it used. This way it was entirely possible to learn the attack sets by heart and how to counter them. In addition to predictable attack patterns, the intercepted radio comms would also give the player a hint of what's to come. It would be up to the player, however, in what order they wanted to get rid of the carriages.

This mockup presents the overview of the level together
with the train model to give the viewer a sense of scale.

The energy shield protecting the train engine disappeared only after all the other parts were destroyed. The wrecked carriages would still travel with the train, as the wheels and suspension system would not be destructible. Additionally, the train could move both forwards and backwards, thanks to the rocket engines mounted on the electromagnetic cannon carriage. All these elements were to result in a demanding, multi-layered boss fight. Sadly, the Chinese Dragon did not make it to the final release, but it is a design we're quite proud of.


While daunting in scope, the boss was not as complicated as it was complex. The sheer number of elements would take at least 3 months of work and we could not justify it. All the carriages, their elements, destruction levels - we are talking about hundreds of models here. Therefore, it was not about the lack of skill or tech. Resigning from the implementation of the Chinese Dragon Train was a decision dictated by reason. All that remains of the boss in the game today are the huge tunnels and multiple tracks on the China map. Perhaps someday the design will find its way to one of our releases.

That is only one of our sick, over-the-top ideas that we never found the time and resources to finish. And since we are already on the topic of insane bosses, the next time we will try to tell you the story of another one - a boss fight comprised of two boss fights. We hope you have a pleasant time this holiday season and that you will have the chance to spend it together with your friends and family.

EXOR Studios


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moddlord1 - - 11,188 comments

This looks great! Tracking this.

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