diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index c53eb6a..75585c0 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -6,40 +6,82 @@ on:
     branches:
       - main
   pull_request:
+  workflow_dispatch: 
 
 jobs:
   test:
-    name: "Test on ${{ matrix.gap-version }}, use-latex: ${{ matrix.use-latex }}, ignore-errors: ${{ matrix.ignore-errors }}"
-    runs-on: ubuntu-latest
+    name: "Test on ${{ matrix.os }}, GAP version ${{ matrix.gap-version }}"
+    runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
         gap-version:
           - 'devel'
+          - '4.15'
           - '4.14'
           - '4.13'
           - '4.12'
           - '4.11'
-          - '4.10'
-        use-latex: ["true","false"]
-        ignore-errors: ["true","false"]
-        exclude:
-          - use-latex: "false"
-            ignore-errors: "false"
-          
+
     steps:
+      - name: "Setup Cygwin"
+        uses: gap-actions/setup-cygwin@v2
+        if: ${{ matrix.os == 'windows-latest' }}
+        
       - name: "Check out this repository"
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: this-action/
-      - uses: gap-actions/setup-gap@v3
+          
+      - name: "Setup GAP"
+        uses: gap-actions/setup-gap@v3
         with:
           gap-version: ${{ matrix.gap-version }}
-      - uses: ./this-action/
+          
+      - name: "Install additional GAP packages"
+        uses: ./this-action/
         with:
           packages: |
-            https://github.com/gap-packages/sophus.git
-            utils
+            Example@devel
+            gap-packages/AutoDoc
+            PrImGrP
+            groupoids@1.80
+            gap-packages/utils@0.92
             https://github.com/gap-packages/grpconst/releases/download/v2.6.2/grpconst-2.6.2.tar.gz
-          use-latex: ${{ matrix.use-latex }}
-          ignore-errors: ${{ matrix.ignore-errors }}
+            https://github.com/gap-packages/forms/releases/download/v1.2.14/forms-1.2.14.zip
+
+      - name: "Check if packages were installed"
+        shell: bash
+        run: |
+          $GAP -A -q <<GAPInput
+            chck := function( pkg, ver )
+              local test;
+              test := TestPackageAvailability( pkg, ver );
+              Print(test,"\n");
+              return test <> fail;
+            end;;
+            bool := [
+              chck( "example",      "4.4.1"      ),
+              chck( "autodoc",      "2026.03.18" ),
+              chck( "primgrp",      "4.0.2"      ),
+              chck( "groupoids",    "1.80"       ),
+              chck( "utils",        "0.92"       ),
+              chck( "grpconst",     "2.6.2"      ),
+              chck( "forms",        "1.2.14"     )
+            ];;
+            QUIT_GAP( ForAll( bool, x -> x ) );
+          GAPInput
+
+  test-scripts:
+    name: "Test the scripts used by this action"
+    runs-on: ubuntu-slim
+
+    steps:
+
+      - name: "Check out this repository"
+        uses: actions/checkout@v6
+
+      - name: "Shellcheck"
+        shell: bash
+        run: shellcheck -e SC2034,SC2154 -o all *.sh
diff --git a/README.md b/README.md
index dc0db00..4867654 100644
--- a/README.md
+++ b/README.md
@@ -6,13 +6,13 @@ This GitHub action installs additional GAP packages.
 
 The action `install-pkg` has to be called by the workflow of a GAP
 package.
-It installs the package(s) using PackageMaker. (TODO: link)
+It installs the package(s) in GAP's `pkg` subfolder.
 
 ## Migration from setup-gap@v2
 
 This package is intended to replace the `gap-pkgs-to-clone` input, though with some
-notable changes. PackageManager will also build the package, and install other
-packages if needed.
+notable changes. Packages will **not** be built, this has to be done by a subsequent
+`build-pkg` action.
 
 
 ### Inputs
@@ -20,25 +20,12 @@ packages if needed.
 The following input is mandatory:
 
 - `packages`:
-  - Space-separated or newline-separated list of packages to install.
-    Can be the name of the package, the link to a git repo (ending in `.git'`'), or
-    the link to a release archive.
-  - default: `'true'`
- 
-The following inputs are all optional:
-
-- `ignore-errors`:
-  - Ignore errors raised by PackageManager. Can be of use when it
-    fails to build documentation that you don't need anyway.
-  - default: `'false'`
-- `use-latex`:
-  - Install and use LaTeX (only works on Linux).
-  - default: `'false'`
-
-
-### What's new in v1
-
-- EVERYTHING
+  - Space-separated or newline-separated list of packages to install. Packages are either
+    given as `package`, as `package@version`, or by an URL pointing to a release archive.
+    Here, `package` can either be the name of a package in the GAP package distribution or
+    the name of a GitHub repository (of the form "org/repo"). The optional suffix `version`
+    is either `latest`, `devel`, or a version number.
+  - default: `''`
 
 ### Examples
 
@@ -63,7 +50,10 @@ jobs:
       - uses: gap-actions/setup-gap@v3
       - uses: gap-actions/install-pkg@v1
         with:
-          packages: 'example'
+          packages: |
+            gap-packages/smallgrp
+            autpgrp@devel
+            https://github.com/gap-packages/primgrp/releases/download/v4.0.2/primgrp-4.0.2.tar.gz
 ```
 
 ## Contact
diff --git a/action.yml b/action.yml
index 577e055..dddc227 100644
--- a/action.yml
+++ b/action.yml
@@ -1,48 +1,87 @@
 name: 'Install packages'
 description: 'Install additional GAP packages'
+
 inputs:
   packages:
-    description: 'Space-separated list of packages to install'
+    description: 'Space-separated or newline-separated list of packages to install'
     required: true
     default: ''
-  ignore-errors:
-    description: 'Ignore errors when installing'
-    required: false
-    default: 'false'
-  use-latex:
-    description: "Install and use latex (only works on Linux)"
-    required: false
-    default: "false"
 
 runs:
   using: "composite"
   steps:
-    - name: "Install TeX Live"
-      if: ${{ inputs.use-latex == 'true' }}
+
+    - name: Install bsdtar
+      if: ${{ runner.os == 'Linux' }}
       shell: bash
-      run: |
-        sudo apt-get install --no-install-recommends texlive-latex-base texlive-latex-recommended texlive-latex-extra texlive-fonts-recommended
-    - name: "Run tests"
+      run: sudo apt install -y libarchive-tools # bsdtar
+
+    - name: Install GAP packages
       shell: bash
       run: |
         # Convert newlines to spaces
-        PKGS=$(echo "${{ inputs.packages }}" | tr '\n' ' ')
-
-        error_found=false
-        # Use `gap` instead of `$GAP` to avoid quitonbreak
-        for pkg in $PKGS; do
-          if ! gap -A <<GAPInput
-            LoadPackage("PackageManager");
-            QUIT_GAP(InstallPackage("${pkg}"));
-        GAPInput
-          then
-            error_found=true
-            echo "::error::Installation of ${pkg} may have failed"
-          fi
-        done
-
-        # Exit unless ignore-errors is set to true
-        if [[ "${{ inputs.ignore-errors }}" != "true" && "$error_found" = "true" ]]; then
-          exit 1
+        PACKAGES=$(echo "${{ inputs.packages }}" | tr '\n' ' ')
+     
+        if [[ "${RUNNER_OS}" = "Windows" ]]; then
+          TMPDIR=$(cygpath -u "${RUNNER_TEMP}/install-pkg")
+        else
+          TMPDIR="${RUNNER_TEMP}/install-pkg"
         fi
+        
+        mkdir -p "${TMPDIR}"
+        DEST="${GAPROOT}/pkg"
+        PKG_DISTRO="${TMPDIR}/package-infos.json"
+        
+        # Needed to get reasonable API limits
+        WGET_HEADER="Authorization: token ${{ github.token }}"
+
+        # Load helper functions
+        source "${GITHUB_ACTION_PATH}/install-pkg-functions.sh"
+        
+        for pkg in ${PACKAGES}; do
+          echo "::group::Installing ${pkg}"
           
+          version="latest"
+
+          # Split off version, if present
+          if [[ "${pkg}" == *@* ]]; then
+            version="${pkg##*@}"
+            pkg="${pkg%@*}"
+          fi
+
+          # Set the $name variable
+          get_pkg_name "${pkg}"
+          pkgdir="${DEST}/${name}"
+
+          if [[ "${pkg}" =~ ^https?://.*\.(tar\.gz|tar\.bz2|zip)$ ]]; then
+            echo "Input is an archive"
+            
+            download_and_extract "${pkg}" "${pkgdir}"
+          else
+            # Set the $repo variable
+            if [[ "${pkg}" =~ .*/.* ]]; then
+              echo "Input is a package repository"
+              repo="${pkg}"
+            else
+              echo "Input is a package name"
+              get_repo_from_name "${name}"
+            fi
+
+            if [[ "${version}" = "devel" ]]; then
+              echo "Cloning development branch of ${repo} to ${pkgdir}"
+              clear_dest "${pkgdir}"
+              git clone -q --depth=1 --single-branch "https://github.com/${repo}.git" "${pkgdir}"
+            else
+              # Set the $archive_url variable and update the $version variable
+              get_archive_url "${repo}" "${version}"
+              
+              # Check if package version is already available
+              if check_pkg_availability "${name}" "${version}"; then
+                  echo "Package ${name} ${version} is already available, skipping."
+                  continue
+              fi
+              
+              download_and_extract "${archive_url}" "${pkgdir}"
+            fi
+          fi
+        done
diff --git a/install-pkg-functions.sh b/install-pkg-functions.sh
new file mode 100644
index 0000000..db90cd7
--- /dev/null
+++ b/install-pkg-functions.sh
@@ -0,0 +1,162 @@
+#!/bin/bash 
+
+# Download archive and extract to folder
+download_and_extract() {
+  local url="$1"
+  local target="$2"
+
+  clear_dest "${target}"
+  local filename
+  filename=$(basename "${url}")
+  echo "Extracting ${filename} to ${target}."
+  
+  local archive="${TMPDIR}/${filename}"
+  wget -qO "${archive}" "${url}"
+  mkdir -p "${target}"
+  bsdtar -xf "${archive}" -C "${target}" --strip-components=1
+  rm "${archive}"
+}
+
+# Create valid archive url from base url and possible formats
+combine_url() {
+  local base="$1"
+  local formats="$2" # newline-separated list
+
+  # Prefer .tar.gz if available
+  if echo "${formats}" | grep -q "^\.tar\.gz$"; then
+    archive_url="${base}.tar.gz"
+  elif echo "${formats}" | grep -q "^\.tar\.bz2$"; then
+    archive_url="${base}.tar.bz2"
+  elif echo "${formats}" | grep -q "^\.zip$"; then
+    archive_url="${base}.zip"
+  else
+    echo "::error::No supported archive format found"
+    exit 1
+  fi
+}
+
+# Get package name
+get_pkg_name() {
+  local base
+  base=$(basename "$1")
+
+  # Remove archive suffix
+  base=$(echo "${base}" | sed -E 's/\.(tar\.gz|tar\.bz2|zip)$//')
+  # Remove version suffix
+  base=$(echo "${base}" | sed -E 's/-[0-9]+(\.[0-9]+)*$//')
+  # Convert to lowecase
+  name=$(echo "${base}" | tr '[:upper:]' '[:lower:]')
+}
+
+# Get archive URL
+get_archive_url() {
+  local repo="$1"
+  version="$2"
+  
+  if [[ "${version}" = "latest" ]]; then
+    echo "Fetching latest release for ${repo}"
+    wget --header="${WGET_HEADER}" -qO "${TMPDIR}/release.json" "https://api.github.com/repos/${repo}/releases/latest"
+  else
+    echo "Selecting oldest release >= ${version}"
+    wget --header="${WGET_HEADER}" -qO "${TMPDIR}/releases.json" "https://api.github.com/repos/${repo}/releases"
+
+    local release
+    release=$(jq -c --arg v "${version}" '
+      map(. + {ver:(.tag_name|sub("^v";""))})
+      | sort_by(.ver)
+      | map(select(.ver >= $v))
+      | .[0]
+    ' "${TMPDIR}/releases.json")
+
+    if [[ "${release}" = "null" ]] || [[ -z "${release}" ]]; then
+      echo "::error::No release >= ${version} found"
+      exit 1
+    fi
+
+    echo "${release}" > "${TMPDIR}/release.json"
+    rm "${TMPDIR}/releases.json"
+  fi
+
+  local asset_url
+  asset_url=$(jq -r '
+    .assets[]
+    | select(.name=="package-info.json")
+    | .browser_download_url
+  ' "${TMPDIR}/release.json")
+  rm "${TMPDIR}/release.json"
+
+  if [[ -z "${asset_url}" ]] || [[ "${asset_url}" = "null" ]]; then
+    echo "::error::Release has no package-info.json asset"
+    exit 1
+  fi
+
+  local info
+  info="${TMPDIR}/package-info.json"
+  wget -qO "${info}" "${asset_url}"
+
+  local archive_base
+  local formats
+  archive_base=$(jq -r '.ArchiveURL' "${info}")
+  formats=$(jq -r '.ArchiveFormats' "${info}")
+  formats=$(echo "${formats}" | tr ' ' '\n')
+
+  version=$(jq -r '.Version' "${info}")
+  echo "Selected version ${version} from ${repo} releases"
+  combine_url "${archive_base}" "${formats}"
+  rm "${info}"
+}
+
+# Get PackageDistro information
+get_package_distro() {
+  if [[ ! -f "${PKG_DISTRO}" ]]; then
+    echo "Downloading packages-infos.json from PackageDistro"
+    local distro="${TMPDIR}/package-infos.json.gz"
+    wget -qO "${distro}" "https://github.com/gap-system/PackageDistro/releases/download/latest/package-infos.json.gz"
+    gunzip "${distro}"
+    if [[ ! -s "${PKG_DISTRO}" ]]; then
+      echo "::error::Could not download PackageDistro json"
+      exit 1
+    fi
+  fi
+}
+
+# Get repository name from package name using PackageDistro
+get_repo_from_name() {
+  local name="$1"
+
+  # Create the required file at $PKG_DISTRO
+  get_package_distro
+
+  local pkg
+  pkg=$(jq -c --arg n "${name}" '.[$n]' "${PKG_DISTRO}")
+
+  if [[ "${pkg}" = "null" ]] || [[ -z "${pkg}" ]]; then
+    echo "::error::Package ${name} not found in PackageDistro"
+    exit 1
+  fi
+
+  # Don't try to get URL from PackageDistro - latest version not be merged yet!
+  local repo_url
+  repo_url=$(echo "${pkg}" | jq -r '.SourceRepository.URL') || {
+    echo "::error::Package ${name} not found in PackageDistro"
+    exit 1
+  }
+  repo=${repo_url#https://github.com/}
+}
+
+# Use GAP to check if package-version combination is already installed
+check_pkg_availability() {
+  local pkg="$1"
+  local ver="$2"
+  gap -A -q <<GAPINPUT
+    QUIT_GAP( TestPackageAvailability( "${pkg}", "${ver}" ) <> fail );
+GAPINPUT
+  return $?
+}
+
+# Remove existing package versions
+clear_dest() {
+  local dest="$1"
+  rm -rf "${dest}"
+  rm -rf "${dest}-*"
+}