System design case study / F2P support economy

Designing a companion economy

A system design case study for an F2P game where every pet needed emotional appeal, mechanical output, duplicate value, and long-term resource demand.

17 pet archetypes 4 AFK modes 60 progression levels 5 evolution gates 4 active slots Pet Food / Soap / Super Soap

HD parrot pet artwork from the pet system

01 / Design problem

Add long-term progression through care and AFK utility

The game already had walking, cooking, quests, teams, collection tasks, and seasonal goals. Pets had to support those loops as AFK helpers, while also creating a deep resource sink and repeat value for basic, duplicate, and premium pets.

Audience fit

Care-based companions matched the Japan live-service focus and a main audience of women around 30-40.

Core-game fit

Pets needed to feed existing loops: ingredients, tickets, treasure, coins, quests, team goals, and seasonal tasks.

Economy fit

Pet Food, Soap, Super Soap, duplicates, and premium pets created multiple reusable reward and purchase surfaces.

Design constraint

The system had to be useful in the background without becoming the whole game.

4Active pet slots expanded the need for multiple pets

4AFK collection modes created clear usage roles

60Levels gave every pet a long visible upgrade path

5Evolution gates converted duplicates into lasting value

02 / System model

A pet moved through discovery, care, output, and evolution

The design connected presentation, economy, and utility into one repeatable loop: find or buy a pet, raise it, assign it to useful work, collect output, then evolve it by consuming duplicates.

Find or acquire

Pets entered through map discovery, events, rewards, loot boxes, and offers.

Rescue and catch

Players freed trapped pets, then used probability and boosts to charm them into joining.

Feed and level

Pet Food drove a 60-level curve with sharp late-game resource demand.

Assign AFK mode

Each active pet worked on treasure, ingredients, coins, or tickets.

Collect output

10-minute action cycles turned stats, mood, and time into stored rewards.

Care and boost

Mood, grooming, Soap, and Super Soap created a care layer with mechanical output.

Merge duplicates

Evolution consumed same-species pets at milestone levels, preserving duplicate value.

Repeat with roles

Four active slots and pet archetypes made multiple pets useful at the same time.

Pets visible on the walking map — **Map presence**Pets appeared in the walking world, making companions feel connected to daily movement.

Pet grooming interaction screen — **Grooming care**The care loop used a direct pet interaction that restored mood and made the helper feel personal.

Pet release minigame scene — **Rescue minigame**Players first freed the trapped pet from rubble, then made a probability throw to charm it into joining them.

Pet catch percentage and element bonus UI — **Visible chance**Element effects and success chance made boosts understandable before spending resources.

03 / Player loop

The loop turned a companion into a progression system

A pet was not only collected. It was acquired, invested into, assigned to a job, and eventually consumed or upgraded through the duplicate economy.

01

Collect

Acquire basic and premium pets through discovery, quests, events, login rewards, loot boxes, and personal offers.

02

Invest

Spend Pet Food, manage mood, groom pets, and merge milestone pets into stronger companions.

03

Specialize

Assign pets as active AFK helpers for treasure, ingredients, coins, or tickets according to their strengths.

04 / Core math

Time, mood, level, and species role became output

Players chose what each active pet should work on. The system then converted 10-minute AFK cycles, mood speed, level base stat, species multipliers, and evolution bonuses into practical rewards.

10mOne AFK action cycle

144Maximum stored action cycles

24hMaximum offline accumulation

4Pets could support the player simultaneously

1Select active pet

2Choose output mode

3Wait for 10-minute cycles

4Collect stored rewards

Treasure

Collection support for valuable finds and task progress.

Ingredients

Cooking and recipe support for repeatable goals.

Gold

Soft-currency support for upgrades and everyday play.

Tickets

Progression and utility support through ticket collection.

Skill stat skill = species multiplier x level base stat x evolution bonus

Gold output gold per action = (2 x luck skill) / 100

Ticket output tickets per action = (0.04 x walk skill) / 100

Treasure output treasure chance = (strength skill x rarity factor) / 100

Ingredient output ingredient chance = (agility skill x rarity factor) / 100

Example pet / Parrot at level 60

One pet becomes four different economic outputs

Using the level-60 base stat of 1,082 with no evolution bonus, the Parrot becomes strongest in Luck and Agility. The useful part is not the hidden stat number itself, but what it turns into during 10-minute AFK cycles.

Gold mode34.6gold per 10-minute action, capped by a 3,116 coin bag Ingredient mode65%common ingredient roll chance per action, capped by a 25 item bag Ticket mode37tickets across a full 24-hour AFK window before storage limits Treasure mode1.6%5-star treasure roll chance per action before mood or evolution bonuses

05 / Archetypes and specialization

Species were not skins; they were economic profiles

Four species multipliers map directly to four AFK outputs, making the collection itself a toolbox. Multiple pets stayed useful because different loops needed different helpers.

effective output = species multiplier × level base stat × evolution bonus

Strength

Treasure collection

Agility

Ingredient collection

Luck

Coin collection

Walk

Ticket collection

Role specialists

The strongest examples create clear collection goals without making every pet interchangeable.

Hattifattener

2.0

Rabbit

1.6

Sakura Dragon

1.8

Crawly

1.8

Archetype multipliers

Each species had a different economic profile

These multipliers were applied on top of the level base stat, creating meaningful differences between pets.

Pet	Agility	Luck	Walk	Strength
Bat	1.2	0.8	0.6	0.4
Cat	0.6	0.8	0.2	0.4
Owl	1.0	0.6	0.8	1.6
Squirrel	1.2	0.4	0.8	0.6
Parrot	1.2	1.6	0.6	0.6
Crawly	0.8	1.2	1.8	1.2
Dragon	0.8	1.2	0.6	0.4
Mouse	0.8	0.4	0.6	0.2
Creep	1.2	1.2	0.8	1.8
Frog	0.6	1.2	1.6	0.6
Hedgehog	0.2	0.8	0.4	0.6
Sakura Dragon	1.2	1.8	0.8	1.2
Air Dragon	0.8	1.4	1.6	1.2
Dog	1.0	0.8	1.6	0.6
Rabbit	1.6	1.0	0.8	1.0
Fluffycat	0.8	1.6	0.8	2.0
Hattifattener	0.8	1.6	0.8	2.0

Element-filtered finds

Air, Water, Ground, and Forest pets randomly search only matching item pools.

Random discovery

The system chooses from matching Item Dex entries and always-allowed items.

Targeted search

Players can replace the random roll with one selected item until the mode changes.

06 / Progression economy

Pet Food carried the long-tail sink

The system used a 60-level food curve, storage caps, and duplicate evolution gates. The important design choice was that late-game investment grew sharply while early levels stayed approachable.

1.30mNormal Pet Food on one straight level 1-60 path

2.46mTotal Pet Food when the duplicate merge tree is included

32Base pets represented by the final companion

1,082Level-60 base stat before species multipliers

Pet Food required by level band

Food costs stayed light early, then became the main long-tail sink after level 40.

Levels 1-10

2,462 Levels 11-20

5,373 Levels 21-30

39,600 Levels 31-40

108,000 Levels 41-50

407,200 Levels 51-60

737,000

Base stat growth

The same base curve powered all four skills before pet-specific multipliers were applied.

Lv 1

100 Lv 10

120 Lv 20

186 Lv 30

288 Lv 40

448 Lv 50

696 Lv 60

1,082

Full level curve

Level-by-level Pet Food, base stat, and storage caps

This is the raw balancing layer behind the cleaner summary charts above.

Level	Pet Food to Next	Total Food Spent	Base Stat	Item Bag	Ticket Bag	Coin Bag
1	54	0	100	5	6	288
2	165	54	102	5	6	294
3	165	219	104	5	6	300
4	213	384	106	5	6	305
5	267	597	108	5	6	311
6	319	864	110	5	6	317
7	373	1,183	113	5	7	325
8	426	1,556	115	5	7	331
9	480	1,982	117	5	7	337
10	Evolution gate	2,462	120	5	7	346
11	480	2,462	155	7	9	446
12	480	2,942	158	7	9	455
13	542	3,422	162	7	9	467
14	542	3,964	165	7	10	475
15	582	4,506	168	7	10	484
16	624	5,088	172	7	10	495
17	666	5,712	175	7	10	504
18	708	6,378	178	7	10	513
19	749	7,086	182	7	10	524
20	Evolution gate	7,835	186	7	11	536
21	3,800	7,835	241	7	14	694
22	3,800	11,635	246	10	14	708
23	4,000	15,435	251	10	14	723
24	4,200	19,435	256	10	15	737
25	4,400	23,635	261	10	15	752
26	4,600	28,035	266	10	15	766
27	4,800	32,635	272	10	16	783
28	4,900	37,435	277	10	16	798
29	5,100	42,335	283	10	16	815
30	Evolution gate	47,435	288	10	17	829
31	10,500	47,435	375	15	22	1,080
32	10,500	57,935	383	15	22	1,103
33	10,900	68,435	390	15	22	1,123
34	11,500	79,335	398	15	23	1,146
35	11,900	90,835	406	15	23	1,169
36	12,500	102,735	414	15	24	1,192
37	12,900	115,235	422	15	24	1,215
38	13,400	128,135	431	15	25	1,241
39	13,900	141,535	439	15	25	1,264
40	Evolution gate	155,435	448	15	26	1,290
41	14,500	155,435	583	20	34	1,679
42	44,000	169,935	594	20	34	1,711
43	45,000	213,935	606	20	35	1,745
44	47,000	258,935	618	20	36	1,780
45	48,000	305,935	631	20	36	1,817
46	50,000	353,935	643	20	37	1,852
47	51,500	403,935	656	20	38	1,889
48	52,900	455,435	669	20	39	1,927
49	54,300	508,335	683	20	39	1,967
50	Evolution gate	562,635	696	20	40	2,004
51	74,000	562,635	905	25	52	2,606
52	75,000	636,635	923	25	53	2,658
53	77,000	711,635	942	25	54	2,713
54	78,000	788,635	961	25	55	2,768
55	80,000	866,635	980	25	56	2,822
56	81,500	946,635	999	25	58	2,877
57	82,900	1,028,135	1,019	25	59	2,935
58	94,300	1,111,035	1,040	25	60	2,995
59	94,300	1,205,335	1,061	25	61	3,056
60	Max	1,299,635	1,082	25	62	3,116

7,835Pet Food across levels 1-20 kept early progress approachable.

147,600Pet Food across levels 21-40 introduced real investment pressure.

1.14mPet Food across levels 41-60 made late-game growth the main sink.

07 / Duplicate economy

Evolution made repeated pets stay valuable

At each gate, two pets of the same species and level became one stronger pet. This turned repeat discoveries, premium pulls, and offer pets into long-term progression instead of dead duplicates.

2:1Same species and same level required at every gate.

32Base pets represented by one naturally built final pet.

31Duplicate pets consumed through the merge tree.

61hTimer sum across the five milestone gates on one straight path.

10

1 hour5 rubies to skip

20

4 hours10 rubies to skip

30

8 hours15 rubies to skip

40

16 hours20 rubies to skip

50

32 hours25 rubies to skip

50%chance of a bonus

Evolution roll

A successful roll adds +10% to one AFK role. The remaining 50% produces no bonus.

Treasure bonus12.5%

Ingredient bonus12.5%

Coin bonus12.5%

Ticket bonus12.5%

08 / Care as a modifier

Care fantasy had mechanical output

Mood was not only presentation. It modified AFK speed, while Soap and Super Soap gave the care loop clear resource value through mood recovery, enhanced ingredients, and pet attraction.

0.6×Mood 0-500

1.0×Mood 501-1,000

1.2×Mood 1,001-2,000

1.5×Mood above 2,000

Walking

Real walking restored mood for every active pet, connecting the companion fantasy back to the core walking loop.

Standard Soap

Grooming added 600 ordinary mood through a small interaction, turning care into a repeatable resource action.

Super Soap

Super Mode let a pet collect enhanced ingredients and attract another pet of the same species.

+600Standard Soap mood from grooming

+600Super Mood from Super Soap

+200Mood restored by one level-up

09 / Reward and store economy

The pet system created reusable reward surfaces

Pet Food, pets, Soap, and Super Soap could appear in free rewards, premium tracks, login rewards, group rewards, loot boxes, direct store packs, and personal offers. The system gave each reward a clear use.

Small pack400

Pet Food for 20 rubies

20 food / ruby

Medium pack1,000

Pet Food for 30 rubies

33.3 food / ruby

Large pack5,000

Pet Food for 50 rubies

100 food / ruby

The large pack is 5× more efficient per ruby than the small pack.

Reward family

Pet Food grew power, pets created collection and duplicate value, Soap restored mood, and Super Soap unlocked temporary high-value actions.

Why it mattered

The same content family could be reused across seasons without becoming meaningless, because each item fed a different part of the loop.

10 / Design reflection

What worked, where pressure built, and what I would revisit

System strengths

Readable species identities
Player-directed AFK output
Long-term value for basic, premium, and duplicate pets
Element-based random and targeted searching
Super Mode creates temporary jackpot potential
Visible storage and output growth

Balance pressure

Steep level 41-60 food wall
50% no-bonus evolution result
Large store efficiency jump
Collection chance may exceed 100%
Selected-item rules rely on client validation

What I would revisit

I would make player-facing stat effects clearer, soften or better explain the 50% no-bonus evolution result, and smooth the late-game food wall without removing the long-tail sink.

Outcome

A collection system where every pet was both a character and an economic decision.

The design linked identity, care, AFK output, duplicate value, progression math, and reusable reward resources into one long-term companion economy.

Game design Systems design Economy balancing Progression design