V3 games

You can play games with your Tamagotchi to improve their mood, have them lose weight and earn Gotchi points.
Your Tamagotchi will need to weight, at least, three grams more than their minimum weight, since that's how much they'll lose if they win the game. Their weight will always decrease, at least, one gram, even if they lose.

[This site] (in Japanese) has helped me figure out some stuff about these games.

The V3 has six games, and the rerelease has one more. I'll explain each of them in order:

GET♪

GET♪

This is the only game you'll have access to during the first stage of your Tamagotchi's life.
It's quite long and you need to get pretty far into it to get a single Happy heart… It's not really worth playing.
The Keitai version is much better simply because you only need to get three points to get a Happy heart and lower their weight by two grams.

You'll see three little bags on the bottom of the screen. Use the Ⓐ & Ⓒ buttons to change which of them is open. You'll get a point if you catch a quaver and two if you catch a double semiquaver. To win, you must get 100 points. If you catch a poop or miss a note, you'll lose the game automatically.

You must get, at least, 36 points to get a Happy heart and lose two grams instead of one… Twelve time as many points as in the Keitai series…
At least, the payout is better:

Score	Stage
Score	Baby Toddler	Teen	Adult Senior
0–2	0	0	0
3–20	10	15	20
21–35	20	30	40
36–50	30	45	60
51–65	50	75	100
66–84	70	105	140
85–99	90	135	180
100	150	225	300

If you get 100 points, your Tamagotchi's happiness will be maxed out and they'll lose three grams.
If you get at least 85 points, their mental health will improve.

BUMP

Your Tamagotchi will unlock this game when they reach the second stage of their life.
The game is the same as on the V2. You are very unlikely to win.

If you can beat the first round consistently, it could be a good way of earning some Gotchi points and lowering your Tamagotchi's weight (they'll lose two grams if they beat the first round.)

There are eight rounds. At the start of each round, your Tamagotchi will come from the left and a rival will appear from the right. They'll face away from each other and, a few moments later, you'll be prompted to PUSH the Ⓑ button. Once you've done it, a gauge will appear on the top of the screen. It seems you need to stop it (pushing Ⓑ once again) when it's as full as possible, but I've lost with a full gauge and won with an almost empty one, so I'm not too sure.
Now, if you don't push Ⓑ as soon as the text shows up, your Tamagotchi will lose for sure.

I don't know what the best strategy to win this game is, but it seems heavier Tamagotchis are more likely to win. However, heavier Tamagotchis will earn fewer points:

Rounds won	Weight
Rounds won	50 g or less	From 51 g to 75 g	From 76 g to 90 g	91 g or more
0	5	5	5	5
1	80	60	40	20
2	160	120	80	40
3	240	180	120	60
4	320	240	160	80
5	400	300	180	100
6	600	450	300	150
7	1200	900	600	300
8	2400	1800	1200	600

Your Tamagotchi must win at least four rounds to get one Happy heart.
If they win all the rounds, their happiness will be maxed out. Their physical health will improve if they beat at least seven rounds.

FLAG

Your Tamagotchi will be able to play this game if they are a teen or older.
It's relatively simple, but it stresses me a little. It has nine rounds, so it's quite long.

You have to make your Tamagotchi raise flags as indicated by the game.
Press Ⓐ to make them raise the black flag on the left, and Ⓒ to make them lift the white one on the right. You may be asked to raise either one or both of them. You'll have to raise the rquested flags three times per round. You'll lose the game if you mess up one time.

Once you've beat a couple rounds… the game will try to trick you!
Sometimes it will show a smaller flag with a shorter beep. You must not press any buttons if this happens.
It'll also show the flags on the opposite side of the screen. Make sure to press the button corresponding to the flag of the same color.

Rounds won	Stage
Rounds won	Teen	Adult Senior
0	4	8
1	8	16
2	10	20
3	20	40
4	30	60
5	50	100
6	70	140
7	100	200
8	150	300
9	300	600

If you win eight rounds, your Tamagotchi's mental health will improve.
Their happiness will be maxed out if you win the game, but you only need to beat three rounds for them to get one Happy heart.

HEADING

Your Tamagotchi will be able to play this game if they are a teen or older.
This is the easiest game.

You must stop the ball from falling to the floor. You have to move your Tamagotchi below it (use Ⓐ & Ⓒ to move them) and make them jump (with Ⓑ) to hit it.
You should move your Tamagotchi to the center after each hit.

You must hit the ball 20 times to win:

Hits	Points
0	0
1	4
2	8
3	12
4	16
5	20
6	30
7	40
8	50
9	60
10	70
11	80
12	90
13	100
14	120
15	140
16	160
17	180
18	200
19	250
20	400

You must hit the ball eight times or more for your Tamagotchi to get a Happy heart.
If they win the game, their happiness will be maxed out and their physical health will improve.

MEMORY

Your Tamagotchi will be able to play this game if they are an adult.
It's not very complex, but it's easy to mess up.

The game lasts twenty rounds. You'll be shown a sequence of arrows at the start of each one. You must repeat it using the Ⓐ (left), Ⓑ (up) & Ⓒ (right) buttons.
The sequence only has two arrows on the first round, but, this amount will increase until it reaches eight.
Mess up once, and it's game over.

You can earn up to 400 Gotchi points, like in HEADING, but it'd take much longer to get to the end.

Rounds	Points
0–2	5
3–5	10
6–8	30
9–11	70
12–14	120
15–17	180
18–19	280
20	400

You must beat six rounds to get a Happy heart.

SPRINT

Your Tamagotchi will be able to play this game if they are an adult.
This game isn't very predictable, just like BUMP.

There are eight rounds. At the beginning, an opponent will show up to race against your Tamagotchi. One of them will fall shortly before reaching the goal, the other one will win.
You must cheer for your Tamagotchi by pressing the buttons as many times as you can.

It seems you can just press whichever button you want. You can just press the same one all the time, like Ⓐ, or alternate between two, like Ⓐ and Ⓑ. Though I guess, if you are only going to press one, it'd make more sense to just use Ⓑ. And, if you are going to alternate, Ⓒ and Ⓐ. But you can just do whatever you want. You may even use Ⓒ and Ⓑ if you wish to do so.

We don't really know how the result is determined…
It's not too hard to get past the first few rounds, but your Tamagotchi will start losing for no reason after a certain point.

The payout can vary a bit on the last rounds.
I think it might have something to do with your Tamagotchi's current stage, but I'm not sure.

Rounds	Points
0	5
1	10
2	30
3	50
4	70
5	90–135
6	120–180
7	200–240
8	400–600

You have to beat four rounds to get a Happy heart.
You only need to beat the first round for you Tamagotchi to lose two grams instead of one. This game could help you lower your Tamagotchi's weight.

HOOPS

Your Tamagotchi will be able to play this game if they are an adult.
This game only appears on the 2024 rerelease.
It's similar to GET♪: a worse version of a Keitai game.

It works like on the Keitai: you have to make your Tamagotchi jump (pressing Ⓑ) so they hit the ball and it goes through the hoop. You have to time the button press correctly for it to work.
On this version, the speed at which the ball falls is very random…
You must score 20 times to win.

You get the same amount of points as on the Keitai.

Score	Points
0–2	0
3–9	10
10–19	50
20–29	70
30	100

You need to score three times to get a Happy heart, like on the Keitai. However, you won't get more than that unless you win the entire game…

Hits	Points
0	0
1	4
2	8
3	12
4	16
5	20
6	30
7	40
8	50
9	60
10	70
11	80
12	90
13	100
14	120
15	140
16	160
17	180
18	200
19	250
20	400

Hits	Points
0	0
1	4
2	8
3	12
4	16
5	20
6	30
7	40
8	50
9	60
10	70
11	80
12	90
13	100
14	120
15	140
16	160
17	180
18	200
19	250
20	400

Hits	Points
0	0
1	4
2	8
3	12
4	16
5	20
6	30
7	40
8	50
9	60
10	70
11	80
12	90
13	100
14	120
15	140
16	160
17	180
18	200
19	250
20	400