How many infantry unit types are ideal for a strategy game roster?

[SeekerOfTruth007]

Right now, these are the infantry I already have, besides workers.

Commando = Standard "do anything" infantry. They have a laser rifle which hits both ground and air.

Hell Hound = Flamer infantry, which is good at killing other infantry, but can't attack air.

Rocket Infantry = Weak vs other infantry, but good at killing Tanks and Mechs.

Mortar Team = Range 3 infantry with a 2 minimum range. Good at killing enemy structures and fortified positions.

Mage = Expensive support caster which can unlock up to 3 spells to control the battlefield.

Here are the vehicles I have so far:

Turbo Quad = An ATV which is good for killing infantry and workers

Tank = Good against all infantry except Rocket Infantry. Excellent for killing Static Defenses.

Mech = Best at cornering and killing air units.

Here are the Air Units so far

Jet Fighter = Good against Tanks and other ground-only specialists

Transport = Heals or repairs units inside

Destroyer = Heavy assault flier with regenerating Shields.

What do you think of these units and what other niches might I employ in the game?

[msc545]

Missing Niches You Could Add
Here are some roles that might naturally fit your ecosystem.

1. Recon / Detection Unit
Purpose:

reveals stealth
extends vision
spots artillery
This creates:

information warfare
ambush mechanics
scouting depth
Could be:

Drone
Scout Bike
Recon Commando

2. Dedicated Anti-Air Infantry
Right now:

Commando can hit the air
Mech counters air
But a fragile infantry AA unit creates:

cheap deterrence
area denial
escort gameplay
Could use:

missiles
lasers
portable railguns

3. Shield / Barrier Unit
Not healer.
Not tank.

Instead:

projects temporary cover
blocks attacks
protects advances
This creates:

breach warfare
formation tactics
escort strategies

4. Stealth Unit
Very dangerous design space.
Must be limited carefully.

Best use:

scouting
sabotage
ambush
NOT direct combat superiority.

5. Mobile Artillery Vehicle
You already have mortars.

But later-game:

long-range siege vehicle
fragile
devastating
This naturally escalates warfare scale.

6. Engineer / Field Builder
Could:

repair
deploy barriers
lay mines
build temporary defenses
This creates battlefield shaping.

7. Electronic Warfare Unit
Near-future setting makes this perfect.

Examples:

disables shields
jams aircraft
reduces enemy range
blocks intercepts
Very thematic.

8. Biological / Chemical Area Denial
ONLY if you want darker battlefield themes.

Could create:

hazard zones
movement denial
attrition corridors

9. Heavy Walker / Siege Mech
Distinct from Tank.

Slow.
Huge.
Terrifying.

Could:

ignore minimum range
crush defenses
absorb punishment
But vulnerable to:

Rocket Infantry
artillery
air strikes

Most Important Observation
Your current roster already supports:

screening
combined arms
flanking
counterplay
siege warfare
air denial
harassment
positional play
That means the core system is probably healthy.

That’s much more important than having 100 units.