There are two distinct cave arrangements in Vanguard. The first cave is navigated during every odd round, and the second cave is navigated during every even round. Each new round begins after you encounter with the Gond. The order of the zones that you will encounter in each cave are as follows:
Cave 1: Mountain Zone, Rainbow Zone, Styx Zone, Rainbow Zone, Stripe Zone, Rainbow Zone, Bleak Zone, City of Mystery.
Cave 2: Mountain Zone, Stripe Zone, Styx Zone, Rainbow Zone, Bleak Zone, City of Mystery.
Starting with Round 2, the speed at which you travel through the caves increases quite a bit, giving you less time to react to an impending collision with the terrain. On the other hand, the increase in speed works in your favor since the amount of distance you must cover in order to complete a zone remains the same. Therefore, you will complete the zones and advance to the next one much more quickly. There are also fewer zones to complete in Cave 2 (due to the absence of two Rainbow Zones), so it takes less time to reach the Gond.
The key to this game is purely survival. While you must shoot enemies in order to keep your energy reserves high, you first priority should be protecting your own ship. Use the strategies listed below to keep your ship out of harm's way.
The Mountain Zone is the most basic horizontally scrolling zone. The enemy Mists and Harleys are more of a threat to you than the terrain. When dealing with Mists, remember that they will only move horizontally, or vertically, but never both. Try to gauge which motion a Mist is currently in, and stay out of its way when it's bobbing up and down. The Harley's are less of a threat to you in terms of collision, but they do dart out ahead of the pack unexpectedly. In both cases, fire constantly, but move up or down as soon as you notice your lasers are hitting an enemy bullet. You can never remove the bullet from the screen, so simply get out of its way. Mountain Zone's tend to be abundant with energy power-ups so grab them every time you can.
The Rainbow Zone occurs every time you encounter a diagonal section of a cave on the map. Between both caves, you will encounter three Rainbow Zone that have you ascending, and one that has you descending. You encounter Helms in the ascending zones and Amnos in the descending zones. There is no difference between them besides color. Each Rainbow Zone is divided into two areas, like all zones. The first half pits your ship against three enemies. The second half increases the number up to five. When an enemy appears in the Rainbow Zone, it is locked to a vertical column. Once you find a space point horizontally, you can never be killed until you remove an enemy. When you remove an enemy, a new one will appear to take it's place. If the enemy you killed was immediately next to your ship, there is a chance that the new enemy will appear in your vertical column. Keep you eye out for the new enemy and move if necessary. You can avoid this by aiming only for enemies that are not your immediate neighbor.
The Styx zone is a lot like the Mountain Zone, but it is far more dangerous for two reasons; it does not contain any energy power-ups, and the terrain squeezes in much closer. When the terrain gets tighter, you have far less maneuvering room, and it becomes more important to create a clear path for yourself through the enemies. It also makes dealing with enemy shots even more difficult, since you must get out of their way, and you have fewer options for safety. The Styx Zone does not always remain tight. It widens out from time to time, but moving around is not recommended. Eventually that space will narrow again and you will have to reposition yourself safely between the terrain. If you don't move much when the terrain is open, you won't have to worry so much about repositioning yourself when the time is right. Instead, you will already be safe.
The Stripe Zone is both the most difficult zone to navigate, and the easiest zone in terms of enemies. The Stripe Zone is composed of a continuous pattern that forces you to choose between a high path and a low path. In general, the low path is a little safer because you have more room to maneuver, although you must contend with the Barrier at the end of every low path. Additionally, energy power-ups appear in the Stripe Zone, but they can only be collected on the lower path. Alternatively, the upper path is much thinner, and always ends with the presence of five Garines which are relatively easy to pick off compared to the Barrier. Either way that you go, two things are always true. The bases that dot the landscape are stationary, do not attack, and are easy to pick off for bonus points. There is also a strange enemy embedded in the ground between the two pathways that extends two tentacles above and below itself that reach into either pathway. Whichever direction you choose, you must be sure to avoid the tentacle that reaches into your choice.
Compared to the other zones, the Bleak Zone isn't much of a challenge. It is the only truly vertically scrolling zone, and it contains two enemies, the Kemlus, and the Romedas. You will encounter the Kemlus first. The weird snake-like enemies can actually boost your score by quite a bit. You are allowed to run into any Kemlus up to three times. Each time you do, you will be awarded 1090 points. If you attempt to do this a fourth time, however, you will be destroyed. After the Kemlus, you must face the Romedas. They are a double threat because when you shoot them, they explode, and that explosion prevents your lasers from reaching higher up until the explosion is gone. So be careful not to travel along a column that contains two Romedas back to back. There's no guarantee that you will destroy both Romedas and be free of their explosion by the time they reach you. Romedas also like to dive bomb at your ship. In later stages, Romedas begin to fire bullets, but unfortunately for them, they can only fire left, where they usually will never hit you.
After you exit the Bleak Zone, you will approach the City of Mystery. You only have one chance to succeed at destroying the Gond here. Whether you succeed or fail, you will be taken immediately to the first zone of the next round. There are a number of thins going on in the Gond's favor. First, he has two rotating barriers protecting him. They line up quite a bit, but they move very fast so you must time your shot well. There are lasers on either side of his cave that shoot at you will you attempt to shoot through his barriers. And the longer you stay int he City, the more the cave fills up with destructive beams that fill in from the bottom of the cave to the top. Only one of you will win this fight. If it is you, you will be awarded a point bonus before being transported to the beginning of the next cave.
