Well, HOW do you gain control of a star system or planet?

I never understood...

You land with your player on a planet, walk around, you can set a bomb, set its time, shoot some enemies, but what should I do furthermore?

If you could explain, it would be very nice. Because I do like the game very much, but no-one could ever explain me this, apparently, essential part of it.

I'll explain from daiva 5's point of view 'cause I'm most familiar with it. Daiva 4 should be fairly similar.

In a planet battle each planet is split up into 4 quadrants. Defeat each one and you conquer the planet. In each of the sectors you have to shoot down enemies until the game tells you that quadrant is 'clear' (indicated in the top right). In case you have a bomb, you don't HAVE TO clear the quadrant to which you assigned the bomb. Note that you CAN clear that sector as well. A planet which needn't be bombed will not be damaged as much. So clearing an entire planet is the best strategy. But bombing is better if you aren't very good at planet battles or if specific quadrants are hard to conquer. If you have assigned a bomb, it will be automatically used when the planet battle time equals zero. WATCH OUT: be sure to never be in that quadrant when the bomb drops or your entire fleet is destroyed!!!

In the beginning I advise to only do planet battles on adjacent planets with low defence. If you have a bomb and don't know which sector is hardest just place it in the fourth sector. Once you have attacked a planet more than once, you know which quadrant is hardest. In that case you could use the bomb in a more tactical way. The amount of energy you have after a planet battle is ended determines how much of your fleet remains. There are instances when you clear all sectors and remain with little to no life. In those cases it might happen that you have no remaining fleet and/ or the planet isn't conquered.

If you want to gain control of a star system you have to bring a fleet to the planet you want. The more powerful fleet you have (i.e. more ships) the more energy you have during planet battles. In order to use weapons during planet battles you have to buy weapons for the fleet you want to attack with. Examples of these weapons are a bomb, barrier or a refill of your HP. Ordinarily you start off with just one fleet, which doesn't have any weapons.

One trick in this game is the use of wardata. I posted some of these codes in this thread. If you use the war data ,you get access to a 6th fleet you ordinarily couldn't create. This sixth fleet is a full fleet of ships with all possible weaponry. With a fleet like that planet battles are much easier.

IIRC planet battles aren't possible if an enemy fleet is in the same system as your fleet is.

Colonies can turn neutral because of several events, for instance due to cival unrest. So don't turn up your taxes to much. Also neutral planets can ally themselves with either you or the enemy.

Hope this makes some sence to you. The game is reasonbly complex although it has a very basic interface.

I need to thank Randam for his tips on finishing Daiva V. I finally did it after all these years, by sending all my fleets at once to planet Bleeder and getting my OM ships upgraded. Who would have thought of that?

Some additional notes on Daiva V:

In planet battles, the map is actually circular, so you can walk straight into the fourth sector by just heading left. Time-wise, I find that it usually makes sense to take out those two sectors first and then move on to the second while leaving the bomb to take out the third if you run out of time (or vice-versa). Knowing which types of enemies are in which sectors obviously helps you choose a strategy beforehand.

My usual strategy at the beginning of the game is to take planets with cheap expendable fleets (e.g. one OM ship) until I've built up my econ enough to be able to sustain more significant losses.

Randam is correct that you can't take a planet if there's an enemy fleet on the planet.

IIRC, wardata gives you a (red) fleet that you control with the second joystick. So you could take a planet with two players, or pick and choose which controls to use.

You can generate custom wardatas by sending a fleet out from planet Sadak to planet 31 (appropriately named Wardata). You do lose the fleet for the current session, of course.

I was never sure whether high tax rates led to unrest or not. It seemed like there was always some sort of revolt going on, no matter how high or low I set my tax rates.

If you practice fleet battles enough, you'll get to the point where you can make them very cost-efficient. E.g. you can usually take out an enemy battleship by sacrificing an OM ship (with asteroid cover) or a cruiser and an OM ship (without asteroid cover).

In fleet battles, it's important to note that neither you nor the enemy can fire missiles through another ship, so (e.g.) stacked battleships only get three laser shots each and only the front battleship gets three missile shots.