The first generation Tamagotchi life cycle progresses through Baby, Child, Teenager, Adult, and potentially Senior stages, with the possibility of death due to poor care or age. The stages typically involve evolving from one form to the next based on how well the Tamagotchi is cared for, and the final adult form depends on the care received during the Teenager stage. 

1. Egg Stage:
The Tamagotchi begins as an egg, which hatches after 5 minutes of setting the clock. 

2. Baby Stage:
The baby stage lasts for 65 minutes, during which the Tamagotchi requires constant care for hunger and happiness. 

3. Child Stage:
After the baby stage, the Tamagotchi evolves into a child (Marutchi), which lasts 24-72 hours, depending on the release. 

4. Teenager Stage:
The child evolves into a teenager, which can last 24-72 hours, and care during this stage determines the final adult form. 

5. Adult Stage:
The teenager evolves into an adult, which is the final stage of the life cycle. 

6. Senior Stage (Optional):
Some releases allow for a Senior stage if the adult remains unmarried. 

7. Death:
The final stage is death, which can occur due to poor care, old age, or, in some versions, sickness or predators. 

To care for a Tamagotchi, you need to regularly feed it, clean its waste, and ensure it's happy and healthy. You can also play games with it and even give it medicine if it gets sick. Remember to turn off the lights at night and be aware of your Tamagotchi's hunger, happiness, and health levels. 

Here's a more detailed breakdown:

Feeding:
Tamagotchis need regular feeding, and different models may have different food options. You can also give them snacks, but overfeeding can be harmful. 

Cleaning:
Tamagotchis will produce waste, which needs to be cleaned up by pressing the appropriate icon. 

Happiness:
You can increase your Tamagotchi's happiness by playing games with it, especially the games that come with the device. 

Health:
If your Tamagotchi gets sick, you'll need to use the medicine icon (or the equivalent, depending on the model) to cure it. 

Discipline:
If your Tamagotchi misbehaves (e.g., refuses to eat when it's hungry), you can discipline it by pressing the appropriate icon. 

Nighttime:
Most Tamagotchis have a nighttime setting where the lights should be turned off. (adults sleep from 10pm to 7am, teens 9pm to 9am, children 8pm-9am, babys 9pm to 7am.) 

Pausing:
Some models allow you to pause the Tamagotchi's lifespan, which can be useful for extending its life or giving it a break. When your away,(school, work, friends, etc) you can pause it to ensure that your Tamagotchi stays healthy. (make sure to change the time when you get back. To pause, hold down A and press C)

Evolution:
Tamagotchis will evolve into different characters over time, and you can sometimes influence this process by how you care for it. (see the life cycle section)

Old Age:
Tamagotchis will eventually die of old age, even with perfect care, but you can use the pausing function to try to delay this.

When the death sequence appears, the Tamagotchi will be lost forever. The user must restart their game afterwards, either by pressing buttons A and C together, or by pressing the Reset button on the back of the device.